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Domestic Water Softeners and Filtration

Written and maintained by SynC.

Rev4
IssuedOct 12, 2026
LicenseCC BY 4.0
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1 Scope

NOTE This standard governs the equipment that treats the whole potable supply to a building at its point of entry: what each treatment stage must remove or condition, how the stages are arranged, how each is built and controlled, how its discharge reaches a drain, and how the assembled train is started, protected, and proven. (1.1)
NOTE The scope begins at the connection downstream of the building water service assembly and ends at the treated water connection to the distribution piping, and it includes the bypass, isolation valves, sample ports, gauges, drain connections, and controls that belong to the treatment equipment. (1.2)
NOTE The following are governed elsewhere and are outside this standard: (1.3)
  • the building water service, the meter, and the backflow assembly protecting the public supply
  • the distribution piping that carries water to and from the equipment, including its materials, sizing, testing, and disinfection procedure
  • water heaters, storage vessels, and the decision recorded at the heater about what scale control it needs
  • pressure boosting equipment and the head calculation that sizes it
  • the floor drain, floor sink, or hub drain receiving the equipment discharge, and every drainage pipe downstream of that receptor
  • insulation of the piping connected to the equipment
  • make-up water pretreatment serving boilers, cooling towers, and hydronic systems
  • point-of-use units at a single fixture or appliance, and the fixtures themselves
  • treatment to dialysis, laboratory, pharmaceutical, process, or pool water quality
1.4 The treatment equipment shall be installed in the locations shown on the plumbing plans.
1.5 Every component of the treatment equipment that contacts potable water shall be certified to NSF/ANSI/CAN 61 for health effects and to NSF/ANSI/CAN 372 for lead content.
1.6 The lead-free limit that NSF/ANSI/CAN 372 verifies is set by federal law, Section 1417 of the Safe Drinking Water Act as amended by the Reduction of Lead in Drinking Water Act, and shall not be waived at the project level.
NOTE Point-of-entry treatment changes the water the whole building receives, so the equipment specified here is where downstream equipment warranties, the fixture and piping water chemistry limits, and the building's water management program all meet; a decision made at this equipment is felt at every outlet. (1.7)

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where the contract documents, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
2.3 The adopted plumbing code shall take precedence over every other reference on any matter that code addresses directly.
Standard Title
IPC International Plumbing Code
UPC Uniform Plumbing Code
NFPA 70 National Electrical Code
ASCE 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures
ASHRAE 188 Legionellosis: Risk Management for Building Water Systems
NSF/ANSI 42 Drinking Water Treatment Units — Aesthetic Effects
NSF/ANSI 44 Residential Cation Exchange Water Softeners
NSF/ANSI 53 Drinking Water Treatment Units — Health Effects
NSF/ANSI 55 Ultraviolet Microbiological Water Treatment Systems
NSF/ANSI 58 Reverse Osmosis Drinking Water Treatment Systems
NSF/ANSI 60 Drinking Water Treatment Chemicals — Health Effects
NSF/ANSI/CAN 61 Drinking Water System Components — Health Effects
NSF/ANSI/CAN 372 Drinking Water System Components — Lead Content
UL 979 Water Treatment Appliances
ASME BPVC Section VIII Division 1 Rules for Construction of Pressure Vessels
ASTM D2187 Physical and Chemical Properties of Particulate Ion-Exchange Resins
AWWA B100 Granular Filter Material
AWWA B102 Manganese Greensand for Filters
AWWA B604 Granular Activated Carbon
USEPA Ultraviolet Disinfection Guidance Manual Validation of Ultraviolet Reactors for Drinking Water Disinfection
Standard Methods for the Examination of Water and Wastewater Analytical Methods for Water Quality Parameters (APHA, AWWA, WEF)
NOTE The NSF/ANSI 44 scope is written around residential softeners, but it is the certification under which commercial cation-exchange softeners are tested and listed, and it is the one the plumbing codes name for drinking water softeners regardless of the size of the building served. (2.4)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before any treatment equipment is procured:
  • product data for each treatment stage, giving the vessel size and construction, the media type and volume, the control valve model, the rated service flow and the pressure drop at it, the backwash and rinse flow rates, the drain connection size, the inlet and outlet connection sizes, and the electrical characteristics
  • the certification listing of each unit and each wetted component under the NSF/ANSI standard that applies to it
  • a sizing calculation for each softener showing the raw water hardness used, the exchange capacity at the design salt dose, the resin volume, the design daily demand, and the resulting interval between regenerations
  • a piping schematic of the treatment train showing every vessel, control valve, bypass, isolation valve, sample port, gauge, drain connection, and air gap, with each valve carrying the tag number it will bear in the field
  • a drain calculation giving the peak backwash and brine rinse flow from each vessel and the resulting flow at each receptor
  • the control sequence, the alarm list, and the monitoring point list for each controller
  • a wiring diagram for each controller and each powered device
Action Submittal Packagecheckbox
☐ Treatment stage product data
☐ NSF/ANSI certification listings
☐ Softener sizing calculation
☐ Treatment train piping schematic with valve tag numbers
☐ Drain flow calculation
☐ Control sequence, alarm list, and monitoring point list
☐ Wiring diagrams
3.1.2 Fabrication and installation of treatment equipment shall not begin until the corresponding action submittals have been reviewed and returned.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following supporting records with, or before, the action submittals:
  • the raw water analysis on which the equipment selection is based, reported by a laboratory or by field test methods the Engineer of Record accepts
  • the resin or media manufacturer's published data for each media, giving the capacity at each salt dose, the operating temperature range, the maximum free chlorine or chloramine exposure, and the backwash rate
  • written confirmation from the sewer authority that regeneration brine and backwash discharge is accepted, or the conditions under which it is accepted
  • seismic anchorage calculations sealed by a registered design professional, or the pre-approved anchorage detail the Contractor intends to use, with the detail's listing identified
  • documentation that the startup technician holds the qualification this standard requires
Informational Submittal Packagecheckbox
☐ Raw water analysis
☐ Resin and media manufacturer data
☐ Sewer authority discharge confirmation
☐ Seismic anchorage calculations or pre-approved detail
☐ Startup technician qualification

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the treatment equipment is accepted:
  • an as-built piping schematic recording the installed configuration, the valve tag numbers as fitted, and the final routing of each drain, overflow, and electrical connection
  • operation and maintenance manuals for each treatment stage, with the recommended maintenance tasks, the media and cartridge replacement intervals, and the regeneration settings tabulated
  • the startup report for each unit, signed by the technician who performed it, recording every controller setting as left
  • the field performance test report required by this standard
  • the water quality results measured before and after each treatment stage at startup
  • warranty documentation for each item of equipment, identifying the coverage period and the date coverage begins
  • a signed receipt from the Owner for the spare parts delivered
Closeout Submittal Packagecheckbox
☐ As-built piping schematic with valve tag numbers
☐ Operation and maintenance manuals
☐ Signed startup reports
☐ Field performance test report
☐ Startup water quality results
☐ Warranty documentation
☐ Spare parts receipt

4 Quality Assurance

4.1 Installer and Startup Qualifications

4.1.1 Each portion of the installation shall be performed by personnel holding the license the Authority Having Jurisdiction requires for that trade.
4.1.2 Startup shall be performed by a technician certified by the equipment manufacturer wherever the manufacturer conditions the warranty on a factory-authorized startup.
4.1.3 Where the manufacturer accepts contractor startup, startup shall be performed by a technician who has completed the manufacturer's training for the equipment class being started.
4.1.4 The Contractor shall have the required qualifications on site and available for inspection before startup begins.

4.2 Treatment Unit Certification

4.2.1 Each cation-exchange softener shall be certified to NSF/ANSI 44.
4.2.2 Each filter furnished for an aesthetic reduction claim, including chlorine, taste, odor, and particulate, shall be certified to NSF/ANSI 42 for that claim.
4.2.4 Each reverse osmosis unit furnished for a contaminant reduction claim shall be certified to NSF/ANSI 58.
4.2.5 Each ultraviolet disinfection unit shall be certified to NSF/ANSI 55 for the class indicated in the datasheet, or validated as the datasheet indicates.
4.2.6 Each chemical fed into the potable supply, including regeneration salt, shall be certified to NSF/ANSI 60.
4.2.7 Each powered treatment appliance shall be listed to UL 979 or to another product safety standard that a Nationally Recognized Testing Laboratory applies to water treatment appliances.
NOTE A unit certification covers a claim at a stated flow and contaminant concentration, so a certified unit operated past its certified flow is no longer the certified product. (4.2.8)
4.2.9 No treatment unit shall be operated at a service flow exceeding the flow at which its certification was earned.

5 Raw Water and Service Conditions

5.1 Raw Water Analysis

NOTE Every treatment selection is made against the water that arrives at the site, and an analysis that is old, sampled from a different source, or missing the parameter that governs a stage produces equipment that is sized for a water the building does not receive. (5.1.1)
5.1.2 The Engineer of Record shall establish the design water quality from Site Water Supply SourceSite Water Supply SourceParameterEach project supplies its own value.site-water-supply-source and Site Water Supply HardnessSite Water Supply HardnessParameterEach project supplies its own value.site-water-supply-hardness.
5.1.3 The raw water analysis used to select the equipment shall report each parameter indicated in the datasheet.
Raw Water Analysis Parameterscheckbox
☑ Total hardness as CaCO3
☑ Calcium and magnesium hardness as CaCO3
☑ Total alkalinity as CaCO3
☑ pH
☑ Total dissolved solids or specific conductance
☑ Chloride
☐ Sulfate
☐ Silica
☑ Total iron and ferrous iron
☑ Manganese
☐ Hydrogen sulfide
☑ Free chlorine residual
☐ Monochloramine residual
☑ Turbidity
☐ Total organic carbon
☐ Ultraviolet transmittance at 254 nm
☐ Total coliform and E. coli
☐ Nitrate
☐ Arsenic
☐ Lead and copper
5.1.4 The analysis used for selection shall be no older at the time of submittal than the age indicated in the datasheet.
Age of Raw Water Analysis at Submittalrange
Not more than
months
612243660
5.1.5 Where the building can draw from more than one source, each source shall be analyzed separately, and the equipment shall be selected for the source that places the greatest load on each stage.
5.1.6 Where the supply is chloraminated, the analysis shall report monochloramine separately from free chlorine.
NOTE Chloramine passes through standard activated carbon far faster than free chlorine does and attacks ion exchange resin and reverse osmosis membranes in the same way, so a supply reported only as total chlorine hides the fact that decides the carbon media and the contact time. (5.1.7)
5.1.8 The Contractor shall evaluate the raw water analysis against the published limits of every media, membrane, lamp sleeve, elastomer, and valve body proposed, and shall report any exceedance before the equipment is ordered.
5.1.9 The Contractor shall not be held responsible for equipment failure caused by water quality outside the published limits of the equipment where the exceedance was reported under this article and the equipment was installed and started up as specified.

5.2 Supply Pressure and Temperature

5.2.1 Every pressure-containing component of the treatment equipment shall be rated for not less than Site Water Supply Pressure MaximumSite Water Supply Pressure MaximumParameterEach project supplies its own value.site-water-supply-pressure-maximum as it arrives at the equipment inlet.
5.2.2 Where the pressure reducing arrangement furnished under Domestic Water PipingDomestic Water PipingResolves to the current adopted revision.sync/domestic-water-piping is located upstream of the equipment, the rating may instead be based on the reduced pressure, provided the pressure reducing valve has no bypass around it.
NOTE A regeneration cycle draws brine by an injector that depends on supply pressure, and below the pressure the valve manufacturer publishes the injector draws no brine, the resin is rinsed but not regenerated, and the softener delivers hard water with no fault indicated. (5.2.3)
5.2.4 The Contractor shall confirm that the supply pressure at the equipment inlet during regeneration remains at or above the minimum the control valve manufacturer publishes for brine draw, and shall report any shortfall before the equipment is ordered.
5.2.5 Treatment equipment shall be installed on the cold water supply, upstream of every water heater and every hydronic heat source.
5.2.6 No treatment stage shall be subjected to a water temperature above the maximum published for its vessel, valve, media, or membrane.
NOTE The pressure drop of the treatment train at design flow is lost to every fixture downstream, and where the supply has little margin that loss is what makes a booster pump necessary; the pump and its head calculation are the subject of Domestic Water Booster PumpsDomestic Water Booster Pump SystemsResolves to the current adopted revision.sync/domestic-water-booster-pumps. (5.2.7)
5.2.8 The Contractor shall report the total pressure drop of the treatment train at the design service flow, taken from the submitted product data, to the Engineer of Record before the equipment is ordered.

5.3 Equipment Room Conditions

5.3.1 The space housing the treatment equipment shall be maintained above freezing throughout the year.
NOTE Resin beads hold water inside their structure and fracture when that water freezes, and a frozen control valve body or brine line cracks before it thaws, so freeze protection is a condition of the equipment surviving its first winter rather than a comfort item. (5.3.2)
5.3.3 Where any portion of the equipment, brine line, or drain line passes through a space subject to freezing, that portion shall be freeze-protected.
5.3.4 The space shall be provided with a floor drain, floor sink, or hub drain able to receive the peak backwash and brine rinse flow of every vessel that can discharge at the same time, together with a brine tank overflow, without flooding the room.
5.3.5 Where no gravity receptor can be provided, a sump with a duplex pump rated for brine shall be provided, and the sump shall alarm on high level to the monitoring interface specified in this standard.
NOTE The receptor itself and the drainage piping downstream of it are furnished under Sanitary Waste And Vent PipingSanitary Waste and Vent PipingResolves to the current adopted revision.sync/sanitary-waste-and-vent-piping; this standard governs the discharge connection and the air gap at the equipment. (5.3.6)
NOTE A composite resin vessel and the cold piping serving it sweat in a humid equipment room, and the condensate collects at the base of the vessel and on the floor beneath it. (5.3.7)
5.3.8 Where the design dew point of the equipment room exceeds the temperature of the entering water, the Contractor shall set the vessels on a base that drains to the receptor rather than on the bare floor.
NOTE Insulation of the piping connected to the equipment, where the condensation control determination requires it, is the subject of Plumbing InsulationPlumbing InsulationResolves to the current adopted revision.sync/plumbing-insulation. (5.3.9)

6 Treatment Train Arrangement

6.1 Treatment Stages and Sequence

6.1.1 The treatment stages provided shall be as indicated in the datasheet.
Treatment Stages Providedcheckbox
☑ Sediment filtration
☐ Activated carbon filtration
☐ Iron and manganese removal
☑ Hardness treatment
☐ Reverse osmosis
☐ Ultraviolet disinfection
☐ Chemical feed
NOTE Each stage protects the one after it: sediment ahead of everything keeps particulate out of resin beds and membranes, oxidized iron is removed before it coats resin, carbon ahead of a membrane strips the chlorine that would destroy it, softening ahead of reverse osmosis prevents hardness scaling on the membrane, and ultraviolet goes last because every upstream stage lowers the turbidity and color that absorb its light. (6.1.2)
6.1.3 Where more than one stage is provided, the stages shall be arranged in the following order of flow unless the datasheet or the Engineer of Record directs otherwise for a named stage: sediment filtration, iron and manganese removal, activated carbon filtration, hardness treatment, chemical feed, reverse osmosis, ultraviolet disinfection.
6.1.4 Where the datasheet positions activated carbon downstream of the softener, the sequence shall place it between the softener and any chemical feed.
6.1.5 Each stage shall be furnished with its own isolation valves, its own bypass where this standard requires one, and its own sample ports, so that any stage can be taken out of service without taking out the stages on either side of it.

6.2 Extent of Treated Service

6.2.1 The fixtures, equipment, and branches that receive water from each treatment stage, and those that are served from the untreated supply, shall be as indicated on the plumbing riser diagram.
NOTE Softening the whole supply protects every heater, fixture, and appliance in the building, and it also raises the sodium content of every outlet and strips the mineral content that makes water taste as expected; serving only the hot water side, or only the equipment that scales, protects what needs protecting while leaving drinking outlets on the raw supply. (6.2.2)
6.2.3 Where the drawings serve any drinking outlet from a softened branch, the Contractor shall provide the blending indicated in the datasheet so that the hardness delivered at that outlet can be set.

7 Hardness Treatment

7.1 Hardness Treatment Method

7.1.1 Requirements in this section apply where the datasheet selects hardness treatment as a provided stage.
7.1.2 The hardness treatment method shall be as indicated in the datasheet.
Hardness Treatment Methodselect
Cation-exchange softening
Template-assisted crystallization conditioning
Polyphosphate sequestrant feed
Electronic or magnetic conditioning
NOTE Cation exchange is the one method on this list that removes hardness ions from the water, and it is the only one that can be certified to NSF/ANSI 44 or that satisfies a downstream equipment warranty written in terms of delivered hardness; it costs salt, a drain, and a regeneration discharge for the life of the building. (7.1.3)
NOTE Template-assisted crystallization converts dissolved hardness into suspended crystals that resist adhering to heated surfaces, with no salt, no drain, and no change in the water's mineral content; the hardness is still in the water, so it does nothing for a warranty that limits delivered hardness, and its performance is established by third-party test data rather than by a consensus certification. (7.1.4)
NOTE A polyphosphate sequestrant holds hardness in solution at moderate temperatures for a limited time, and loses that hold as the water is heated and as it stands, which confines it to cold water and short residence times. (7.1.5)
NOTE Electronic and magnetic conditioners apply a field to the pipe with no change in water chemistry; no consensus test standard or certification measures their performance, so a project selecting one has no certified claim to verify at startup. (7.1.6)
7.1.7 Where any downstream water heater, boiler, or appliance carries a warranty conditioned on a maximum delivered hardness, the hardness treatment method shall remove hardness ions to at or below that limit.
NOTE The scale control decision recorded at each water heater under Water HeatersCommercial Water HeatersResolves to the current adopted revision.sync/water-heaters is satisfied by the equipment furnished under this standard; the two standards are to agree, and where they do not, the heater's published hardness limit governs the selection here. (7.1.8)

7.2 Softener Tank Configuration

7.2.1 Requirements in this section and the following softener sections apply where the datasheet selects cation-exchange softening.
7.2.2 The softener tank configuration shall be as indicated in the datasheet.
Softener Tank Configurationselect
Single tank
Twin tank alternating with one tank in service
Duplex parallel with both tanks in service and staggered regeneration
Multiple tanks in progressive flow with tanks brought online by demand
NOTE A single tank is out of service while it regenerates and the building draws hard water through the bypass during that interval; a twin alternating arrangement keeps one tank in service at all times at the cost of a second vessel and a second resin charge, a duplex parallel arrangement carries the full flow across two tanks and loses half its capacity rather than all of it during a regeneration, and a progressive flow arrangement brings tanks online as demand rises so that each tank runs near its rated flow instead of idling at low velocity. (7.2.3)
7.2.4 Where the building cannot accept hard water during a regeneration, the configuration selected shall keep at least one tank in service throughout every regeneration.
NOTE A softener bed held at very low velocity for long periods channels, and water finds a path through the resin without contacting most of it; a twin alternating or progressive flow arrangement is as much about keeping each tank at a working velocity as about continuity of soft water. (7.2.5)

7.3 Regeneration Arrangement and Initiation

7.3.1 The regeneration arrangement shall be as indicated in the datasheet.
Regeneration Arrangementradio
● Automatic regeneration on site
○ Portable exchange tanks regenerated off site
NOTE A portable exchange arrangement removes the brine tank, the salt deliveries, and the regeneration discharge from the building, and replaces them with a service visit that swaps the exhausted tank for a regenerated one; where the sewer authority prohibits brine discharge, it is the arrangement that keeps ion exchange available. (7.3.2)
7.3.3 Where the datasheet selects portable exchange tanks, the Contractor shall furnish the tank connections, isolation valves, and bypass so that a tank can be exchanged without interrupting service to the building.
7.3.4 Regeneration initiation shall be as indicated in the datasheet.
Regeneration Initiationselect
Meter initiated, immediate on exhaustion of capacity
Meter initiated, delayed to a preset hour with a reserve capacity
Time clock on a fixed calendar interval
Hardness sensor on the treated water
Remote initiation from the building automation system
NOTE A meter counts the treated volume and regenerates when the capacity is used, so salt and water consumption follow actual demand; immediate initiation suits a twin alternating arrangement where the other tank carries the load, while delayed initiation suits a single tank by holding a reserve until the building's low-use hour. A time clock regenerates on the calendar whether or not the capacity was used, which wastes salt in a lightly used building and lets a heavily used one go hard between cycles. A hardness sensor acts on the result rather than the volume, and remote initiation lets the building automation system schedule regeneration around the building's own operating pattern. (7.3.5)
7.3.6 Unless the datasheet selects time clock initiation, the controller shall also initiate a regeneration after a settable number of days has elapsed without one.
NOTE Resin that goes weeks between regenerations in a lightly used building fouls with organics and iron and can develop a bacterial population; the calendar override exists to exercise the bed regardless of volume. (7.3.7)
7.3.8 Brine dose control shall be as indicated in the datasheet.
Brine Dose Controlradio
○ Fixed salt dose per regeneration
○ Proportional salt dose scaled to the capacity used
NOTE A fixed dose regenerates the full bed every cycle regardless of how much was exhausted; proportional brining measures what was used and scales the salt to it, which reduces salt consumption where regeneration is initiated early by a delayed schedule or a calendar override. (7.3.9)
7.3.10 Regeneration flow direction shall be as indicated in the datasheet.
Regeneration Flow Directionradio
● Co-current, brine introduced in the direction of service flow
○ Counter-current, brine introduced opposite to service flow
NOTE Counter-current brining regenerates the outlet end of the bed most completely, which lowers the hardness that leaks through at the start of a service run and uses less salt for the same capacity; it depends on the bed staying in place during brining, so it needs either a valve designed for it or a flow rate low enough not to lift the resin. (7.3.11)

7.4 Regeneration Chemistry and Brining

7.4.1 The regenerant shall be as indicated in the datasheet.
Regenerantradio
● Sodium chloride
○ Potassium chloride
NOTE Potassium chloride exchanges potassium rather than sodium onto the treated water, which matters where occupants or processes are sodium-restricted; it costs more per pound, delivers somewhat less capacity per pound, and is used at a higher dose to reach the same result. (7.4.2)
7.4.3 The design salt dose shall be as indicated in the datasheet.
Design Salt Doserange
lb/ft³
4568101215
NOTE Salt dose trades capacity against efficiency: each additional pound of salt per cubic foot of resin restores less additional capacity than the pound before it, so the highest dose delivers the most grains per regeneration and the lowest delivers the most grains per pound of salt. The catalog capacity of a softener is its capacity at the highest dose, and a unit selected on that number and operated at an efficient dose delivers well under its catalog figure. (7.4.4)
7.4.5 The salt efficiency the softener delivers shall be as indicated in the datasheet.
Salt Efficiencyrange
Not less than
grains/lb
150020002500300033504000450050006000
Derived — the design salt dose and the resin manufacturer's published capacity at that dose, and any minimum salt efficiency the jurisdiction imposes on self-regenerating softeners (by default)
NOTE NSF/ANSI 44 permits a salt efficiency claim only at or above a stated grains-per-pound figure, and some jurisdictions set a higher minimum for any softener that regenerates on site, so the efficiency a project must reach is a fact of the jurisdiction and the resin rather than a preference. (7.4.6)
7.4.7 Where the jurisdiction imposes a minimum salt efficiency, the design salt dose shall be one at which the selected resin delivers that efficiency.
7.4.8 Where the jurisdiction prohibits self-regenerating softeners or restricts brine discharge to the sanitary sewer, the Contractor shall report the restriction before the equipment is ordered, and the Engineer of Record shall direct whether the regeneration arrangement, the hardness treatment method, or the discharge route is changed.

7.5 Exchange Capacity and Flow Rating

7.5.1 The exchange capacity per tank shall be as indicated in the datasheet.
Exchange Capacity per Tankrange
grains
1000020000300004500060000900001200001500002000003000004500006000009000001200000180000024000003000000
Per drawings — the plumbing equipment schedule (deferred by default)
7.5.2 The resin volume per tank shall be as indicated in the datasheet.
Resin Volume per Tankrange
ft³
0.511.52345710152030405075100150
Derived — the exchange capacity per tank divided by the resin manufacturer's published capacity per cubic foot at the design salt dose (by default)
7.5.3 The design service flow rate shall be as indicated in the datasheet.
Design Service Flow Raterange
GPM
2581015203040608010015020030040060080010001500
Per drawings — the plumbing equipment schedule (deferred by default)
7.5.4 The pressure drop across each softener at the design service flow shall not exceed the value indicated in the datasheet.
Pressure Drop at Design Service Flowrange
Not more than
psi
510152025
NOTE Flow through a resin bed is limited at both ends: too high a velocity compacts the bed, raises the pressure drop, and lets hardness slip through before it can exchange; too low a velocity lets the bed channel. The resin volume that satisfies the capacity and the vessel diameter that satisfies the flow are two different constraints, and a tank that meets one and not the other is undersized. (7.5.5)
7.5.6 Each softener shall deliver the treated water hardness this standard requires at the design service flow rate, continuously, without exceeding the pressure drop limit.

7.6 Treated Water Hardness and Blending

7.6.1 The maximum hardness of the treated water leaving the softener, measured during the service run before the capacity is exhausted, shall be as indicated in the datasheet.
Treated Water Hardness Limitrange
Not more than
gpg
0.51235
NOTE One grain per gallon is the threshold below which water is conventionally called soft, and it is the hardness that NSF/ANSI 44 uses to define the end of a service run; a lower figure is reached by counter-current brining or a higher salt dose, and a higher figure is a deliberate blend. (7.6.2)
7.6.3 Hardness blending shall be as indicated in the datasheet.
Hardness Blendingselect
None
Blending adjustment integral to the control valve
External blending valve with a lockable setting
NOTE Fully softened water is the norm, and blending is used where the building wants a set residual hardness, as for drinking outlets or for corrosion control on a soft and aggressive supply; an integral adjustment is simple and coarse, while an external blending valve can be set, locked, and verified by a hardness test at its outlet. (7.6.4)
7.6.5 Where blending is provided, the Contractor shall set it at startup to deliver the hardness the Engineer of Record directs and shall record the setting in the startup report.

8 Softener Construction

8.1 Ion Exchange Resin

8.1.1 The ion exchange resin shall be a strong acid cation resin of sulfonated styrene-divinylbenzene copolymer in the sodium form, certified to NSF/ANSI/CAN 61.
8.1.2 The resin type shall be as indicated in the datasheet.
Resin Typeselect
Gel, standard crosslinkage
Gel, high crosslinkage
Macroporous
Fine mesh
8.1.4 The resin manufacturer's published values for capacity, moisture content, bead size distribution, and whole bead count shall be reported per ASTM D2187 in the product data.
8.1.6 Where the free chlorine or chloramine residual of the supply exceeds the maximum the selected resin manufacturer publishes for continuous exposure, the Contractor shall report the exceedance before the equipment is ordered.
8.1.7 Each vessel shall be furnished with a gravel or graded support underbed where the resin manufacturer or vessel manufacturer requires one for the distributor furnished.

8.2 Resin Pressure Vessels

8.2.1 The resin vessel construction shall be as indicated in the datasheet.
Resin Vessel Constructionselect
Filament-wound fiberglass over a polyethylene liner
Carbon steel, epoxy lined
Carbon steel, rubber lined
Stainless steel
NOTE A composite vessel is the lightest, the least expensive, and immune to corrosion, which is why it carries the default; it is made in diameters up to a limit the manufacturer publishes, above which a lined steel vessel is the available product. An epoxy lining is the economical steel lining and is repaired by recoating, a rubber lining resists brine and abrasion for longer at a higher cost, and stainless steel removes the lining as a maintenance item but is itself attacked by chloride at the concentrations brine reaches. (8.2.2)
8.2.3 The vessel working pressure rating shall be as indicated in the datasheet.
Resin Vessel Working Pressure Ratingrange
Not less than
psi
100125150200250
8.2.4 Steel vessels shall be constructed and stamped to ASME BPVC Section VIII Division 1 where the adopted code or the Authority Having Jurisdiction requires a stamped vessel for the vessel diameter and pressure.
8.2.5 Composite vessels shall carry a published working pressure rating and a published burst test pressure, and the manufacturer shall state the maximum operating temperature at which the working pressure rating applies.
8.2.6 Each vessel shall be furnished with an upper and lower distributor that retain the resin at the backwash flow rate without releasing beads to the drain and without restricting the service flow.
8.2.7 Each vessel exceeding the size that can be lifted and emptied by hand shall be furnished with a resin loading port and a resin removal connection positioned so the bed can be changed without removing the vessel.

8.3 Control Valves

8.3.1 The control valve type shall be as indicated in the datasheet.
Control Valve Typeselect
Single multiport valve, piston type
Single multiport valve, rotary disc type
Diaphragm valve nest operated by a stager
Individually actuated valves operated by a programmable controller
NOTE A single multiport valve carries every cycle in one body and is the valve on nearly every softener below the size at which its flow capacity runs out; a piston seals on a stack of seals and spacers that wear with grit, while a rotary disc seals on a flat ceramic face that tolerates it. A diaphragm valve nest spreads the cycles over several valves driven by a hydraulic or pneumatic stager and serves the flows a multiport valve cannot. Individually actuated valves under a programmable controller cost the most and give the operator a controller that reports every valve position and can be integrated as the building automation system is. (8.3.2)
8.3.3 The control valve body material shall be as indicated in the datasheet.
Control Valve Body Materialselect
Lead-free copper alloy
Engineered polymer
Stainless steel
NOTE A lead-free copper alloy body carries the highest pressure and temperature ratings of the three and is the body on most commercial multiport valves; an engineered polymer body resists brine and dezincification and is the lighter and less expensive body on smaller valves; stainless steel is selected where a copper alloy would be attacked by the water or where the Owner standardizes on it. (8.3.4)
8.3.5 Each control valve shall be furnished with a brine injector sized for the vessel diameter and the resin volume it serves.
8.3.6 Each control valve shall be furnished with a flow meter where the datasheet selects meter initiated regeneration or any monitoring output that reports treated volume.
8.3.7 Each control valve shall be furnished with a backwash flow control that holds the backwash rate at the resin manufacturer's published rate regardless of supply pressure.
NOTE A backwash that runs faster than the resin manufacturer's rate lifts resin out of the vessel to the drain, and one that runs slower leaves the bed compacted and fouled; the flow control is what makes the rate independent of the pressure on the day. (8.3.8)
8.3.9 Each control valve shall retain its programmed settings through a loss of power for not less than 24 hours and shall resume the cycle in progress or return to service when power is restored.

8.4 Brine System

8.4.1 The brine tank arrangement shall be as indicated in the datasheet.
Brine Tank Arrangementselect
Separate brine tank for each resin vessel
Cabinet with the brine compartment integral to the softener
One brine tank shared by multiple resin vessels
NOTE A separate brine tank holds the salt the building needs between deliveries and can be sized independently of the resin vessel, which is why it is the arrangement on commercial softeners; a cabinet puts the brine compartment under the resin vessel in one footprint, holds a smaller salt charge, and suits a small unit in a confined space; a shared tank serves a twin or multi-tank softener from one salt charge at the cost of a larger single tank and a refill system sized for the total draw. (8.4.2)
8.4.3 The brine tank shall store salt for not less than the number of days of operation indicated in the datasheet, at the design regeneration frequency and the design salt dose.
Brine Salt Storagerange
Not less than
days
71430456090
8.4.4 The brine tank shall be polyethylene or another material unaffected by saturated brine, with a cover, a salt grid or platform that keeps the salt above the brine level where the manufacturer's design uses one, and a brine well containing the float valve.
8.4.5 Brine refill shall be automatic, with a float valve that stops refill at the set brine level and a safety float that closes independently of the primary float.
NOTE A stuck refill float overfills the brine tank through the overflow continuously until someone notices; the safety float is the second line that turns that into a reported event rather than a flooded room. (8.4.6)
8.4.7 The brine tank shall be furnished with a gravity overflow connection that discharges to the receptor through its own air gap, with no valve in the overflow line.
8.4.8 The brine line between the brine tank and the control valve shall be run with no low point in which air can collect and no fitting that restricts the injector draw.

9 Sediment Filtration

9.1 Requirements in this section apply where the datasheet selects sediment filtration as a provided stage.
9.2 The sediment filter type shall be as indicated in the datasheet.
Sediment Filter Typeselect
Replaceable cartridge in a single or manifolded housing
Replaceable bag in a bag housing
Backwashing multimedia pressure filter
Automatic self-cleaning screen filter
Manual flushing screen or spin-down filter
NOTE A cartridge gives the finest rating at the lowest first cost and is consumed; where the turbidity load is low it runs for months, and where it is high it is a weekly chore. A bag holds more solids per change at a coarser rating. A backwashing multimedia filter removes the solids load continuously, needs a drain and a backwash supply, and is the filter on a turbid well supply. A self-cleaning screen filter removes particles down to its screen rating with a brief automatic flush rather than a full backwash, and a manual screen filter is the coarse protection a utility supply with occasional main-break debris needs. (9.3)
9.4 The sediment filter particle rating shall be as indicated in the datasheet.
Sediment Filter Particle Ratingrange
µm
151020255075100150200
NOTE The finer the rating, the shorter the interval between changes on the same water and the higher the clean pressure drop; the rating a stage needs is set by what it protects, with membranes and ultraviolet units asking for the finest and a resin bed tolerating a coarser one. (9.5)
9.6 The sediment filter rated flow shall be as indicated in the datasheet.
Sediment Filter Rated Flowrange
GPM
2581015203040608010015020030040060080010001500
Per drawings — the plumbing equipment schedule (deferred by default)
9.7 Each cartridge and bag housing shall be furnished with a pressure gauge on its inlet and on its outlet, or a differential pressure gauge across it, so that the change-out condition can be read.
9.8 Each cartridge and bag housing shall be furnished with a pressure relief or vent so that the housing can be depressurized before it is opened.
9.9 Multimedia filter media shall conform to AWWA B100, with the layer depths and grades the filter manufacturer publishes for the vessel.
9.10 A backwashing filter shall be furnished with a backwash flow control and shall be sized so that its backwash rate at the installed vessel diameter can be supplied by the building service without starving the fixtures in use.
9.11 The Contractor shall replace each cartridge and bag when the differential pressure across it reaches the value the filter manufacturer publishes for the housing, or at the interval the manufacturer publishes, whichever occurs first, through the date of acceptance.

10 Activated Carbon Filtration

10.1 Requirements in this section apply where the datasheet selects activated carbon filtration as a provided stage.
10.2 The activated carbon media shall be as indicated in the datasheet.
Activated Carbon Mediaselect
Granular activated carbon, coconut shell
Granular activated carbon, bituminous coal
Catalytic activated carbon
Carbon block cartridge
NOTE Coconut shell carbon carries a tighter pore structure that favors small organic molecules and chlorine, and bituminous carbon a broader one that favors larger organics and color; either removes free chlorine readily. Chloramine is removed by ordinary carbon only slowly and is the case for which catalytic carbon exists, which removes it at a fraction of the contact time. A carbon block cartridge is the consumable form, with the finest particulate rating of the four and the shortest life, and it is the carbon on a small train that has no backwash drain. (10.3)
10.4 Granular activated carbon shall conform to AWWA B604 and shall be certified to NSF/ANSI/CAN 61.
10.5 The position of the carbon stage shall be as indicated in the datasheet.
Activated Carbon Positionselect
Upstream of the softener on the full treated flow
Downstream of the softener on the full treated flow
On a dedicated branch serving taste and odor loads
NOTE Carbon ahead of the softener strips the chlorine that oxidizes resin and extends resin life; carbon after the softener leaves the resin exposed and keeps the bed itself from passing resin fines into the carbon. Either position on the full flow removes the disinfectant residual from the whole building, and a distribution system with no residual is one in which biofilm and Legionella are controlled by temperature and flow alone. A dedicated branch removes chlorine taste at the outlets that care and leaves the residual in the rest of the building. (10.6)
10.7 Where the datasheet positions carbon on the full treated flow, the Engineer of Record shall record the loss of residual disinfectant downstream of the carbon stage in the water management program the project maintains under ASHRAE 188.
10.8 The empty bed contact time of each granular carbon vessel at the design service flow shall be as indicated in the datasheet.
Carbon Empty Bed Contact Timerange
Not less than
min
12357101520
Derived — the disinfectant residual carried by Site Water Supply SourceSite Water Supply SourceParameterEach project supplies its own value.site-water-supply-source, whether free chlorine or chloramine, and the carbon manufacturer's published contact time for its removal at the design service flow (by default)
NOTE Contact time is the quantity that sizes a carbon vessel, and it is set by what the carbon must remove: free chlorine is removed in a short contact, chloramine in a far longer one on standard carbon, and dissolved organics in a contact set by the loading the carbon manufacturer publishes for the compound. (10.9)
10.10 Each granular carbon vessel shall be furnished with a control valve that backwashes the bed at the carbon manufacturer's published rate, with a backwash flow control, and that returns the bed to service with a rinse.
NOTE A carbon bed removes the residual that would otherwise suppress bacterial growth, and the bed is itself a surface on which bacteria colonize; the backwash and the change-out interval are what keep that population from reaching the building. (10.11)
10.12 The Contractor shall record in the operation and maintenance manual the carbon change-out interval the manufacturer publishes for the loading at the design flow, and the Owner's water management program shall carry that interval as a maintenance task.
10.13 The Contractor shall replace each carbon block cartridge when the differential pressure across it reaches the value the manufacturer publishes or at the interval the manufacturer publishes, whichever occurs first, through the date of acceptance.

11 Iron and Manganese Removal

11.1 Requirements in this section apply where the datasheet selects iron and manganese removal as a provided stage.
NOTE Dissolved ferrous iron passes a sediment filter, oxidizes to insoluble ferric iron on contact with air or chlorine, and then stains fixtures and coats resin; manganese does the same at a lower concentration and a higher pH. A softener removes ferrous iron by exchange up to a concentration the resin manufacturer publishes, and above that an oxidizing stage ahead of the softener is what keeps the bed clean. (11.2)
11.3 The iron and manganese removal method shall be as indicated in the datasheet.
Iron and Manganese Removal Methodselect
Ion exchange in the softener with a resin cleaner feed
Oxidizing media filter without a separate oxidant feed
Air injection oxidation ahead of a media filter
Chemical oxidant feed ahead of a media filter
NOTE Exchange in the softener handles low ferrous iron with no additional vessel and relies on a periodic resin cleaner to strip what accumulates. An oxidizing media filter removes iron and manganese on a catalytic surface and regenerates that surface by backwash, or on a greensand surface regenerated by permanganate or chlorine, with no separate feed equipment. Air injection oxidizes the iron in a head of air inside the vessel ahead of the media and removes the chemical feed entirely, at the cost of a venturi or compressor and a vessel tall enough to hold the air. A chemical oxidant feed handles the highest concentrations and the manganese that air will not oxidize at the supply pH, and it brings chemical storage and a feed pump with it. (11.4)
11.5 Manganese greensand media shall conform to AWWA B102.
11.6 Each oxidizing media vessel shall be furnished with a control valve that backwashes the bed at the media manufacturer's published rate, with a backwash flow control, and that regenerates the media where the media requires a regenerant.
11.7 Where the raw water carries hydrogen sulfide, the removal method selected shall be one the media manufacturer publishes as removing it at the measured concentration.

12 Reverse Osmosis

12.1 Requirements in this section apply where the datasheet selects reverse osmosis as a provided stage.
NOTE A point-of-entry reverse osmosis unit treats the whole supply to a building, and the arrangement that makes that practical is a unit producing permeate continuously into an atmospheric storage tank, with a repressurization pump delivering from the tank to the building. (12.2)
12.3 The reverse osmosis arrangement shall be as indicated in the datasheet.
Reverse Osmosis Arrangementselect
Full flow through the membranes with permeate storage and repressurization
Partial flow through the membranes blended with treated bypass water
Direct feed through the membranes without storage
NOTE Full-flow treatment with storage lets a small membrane array run continuously to meet a peak that would otherwise need a large one, and the storage tank and repressurization pump are the price. Partial flow blends permeate with softened bypass water to a set dissolved solids target and reduces the membrane array, the reject volume, and the aggressiveness of the delivered water. Direct feed without storage needs an array sized for the instantaneous peak and a feed pump that follows demand, and it is the arrangement where the building has no space for a tank. (12.4)
12.5 Membranes shall be thin-film composite polyamide elements in fiberglass or stainless steel pressure vessels, and the unit shall be certified to NSF/ANSI 58 where the datasheet relies on a contaminant reduction claim.
NOTE A thin-film composite membrane is destroyed by free chlorine at concentrations far below a utility residual and by hardness scaling on its surface, which is why a point-of-entry reverse osmosis unit is always preceded by dechlorination and by softening or an antiscalant feed, and why the carbon and softener stages upstream are part of its protection rather than separate conveniences. (12.6)
12.7 The feedwater to the membranes shall be dechlorinated by activated carbon or by a sodium bisulfite feed to a free chlorine concentration at or below the membrane manufacturer's published limit.
12.8 The feedwater to the membranes shall be softened, or an antiscalant certified to NSF/ANSI 60 shall be fed, so that the concentrate at the design recovery remains below the scaling limits the membrane manufacturer publishes.
12.9 The feedwater to the membranes shall pass a sediment filter rated at or finer than the membrane manufacturer publishes.
12.10 The design recovery shall be as indicated in the datasheet.
Reverse Osmosis Design Recoveryrange
%
2535506070758085
Derived — the raw water analysis after the upstream treatment stages, evaluated by the membrane manufacturer's projection against the scaling and fouling limits of the selected element at the design feedwater temperature (by default)
NOTE Recovery is the share of feedwater that becomes permeate, and the rest goes to drain as concentrate; a higher recovery wastes less water and concentrates the dissolved solids further against the membrane, so the achievable figure is a projection on the analysis rather than a preference. (12.11)
12.12 The membrane array shall be selected so that the permeate rate at Site Water Supply Temperature MinimumSite Water Supply Temperature MinimumParameterEach project supplies its own value.site-water-supply-temperature-minimum meets the design permeate rate.
NOTE Membrane productivity falls as the feedwater cools, by a few percent for each degree, and an array rated at the standard test temperature and fed cold winter well water produces well under its rating at the time of year the building needs it most. (12.13)
12.14 The unit shall be furnished with a feed pressure gauge, a concentrate pressure gauge, permeate and concentrate flow meters, a permeate conductivity or total dissolved solids monitor with an alarm, a low feed pressure cutout, and a storage tank level control that stops production at high level and starts it at low level.
12.15 The unit shall be furnished with an automatic flush of the membranes with permeate or low-pressure feedwater at shutdown.
12.16 The concentrate shall discharge to the receptor through an air gap, with no valve in the concentrate line downstream of the unit's own concentrate control valve.
12.17 Permeate conditioning shall be as indicated in the datasheet.
Reverse Osmosis Permeate Conditioningselect
None
Calcite contactor adding hardness and alkalinity
Blending with softened bypass water to a dissolved solids target
Chemical feed adjusting pH and alkalinity
NOTE Permeate has had nearly all of its alkalinity and hardness removed, so its pH is low, its buffering is gone, and it dissolves copper and the zinc in brass as it passes through the building; conditioning restores enough mineral content to make the water stable, by dissolving calcite, by blending back a portion of softened water, or by feeding alkali, each of which gives up a little of the purity the membranes produced. (12.18)
12.19 Unless the datasheet selects permeate conditioning, the distribution piping and fittings downstream of the reverse osmosis unit shall be materials that Domestic Water PipingDomestic Water PipingResolves to the current adopted revision.sync/domestic-water-piping permits for a water of the permeate's pH and alkalinity.
12.20 The permeate storage tank shall be an opaque, closed atmospheric tank certified to NSF/ANSI/CAN 61, with a screened vent, an overflow to the receptor through an air gap, and a drain, and the tank shall be sized so that its contents turn over within the period the Engineer of Record directs.
NOTE The repressurization pump, its controls, and the pressure it delivers to the building are furnished under Domestic Water Booster PumpsDomestic Water Booster Pump SystemsResolves to the current adopted revision.sync/domestic-water-booster-pumps; this standard governs the tank it draws from. (12.21)

13 Ultraviolet Disinfection

13.1 Requirements in this section apply where the datasheet selects ultraviolet disinfection as a provided stage.
NOTE Ultraviolet light at the germicidal wavelength inactivates bacteria, viruses, and protozoa as the water passes the lamp, leaving no residual in the water and adding nothing to it; its dose is the product of lamp intensity and exposure time, and anything that absorbs or scatters the light, including turbidity, color, iron, and a fouled sleeve, lowers the dose the organism receives without changing anything the operator can see. (13.2)
13.3 The ultraviolet certification class shall be as indicated in the datasheet.
Ultraviolet Certification Classselect
NSF/ANSI 55 Class A
NSF/ANSI 55 Class B
Validated to the USEPA Ultraviolet Disinfection Guidance Manual
NOTE Class A under NSF/ANSI 55 is the class for water not known to be microbiologically safe, with a dose and a monitoring sensor that together make a claim of disinfection; Class B is the supplemental class for water already considered safe, at well under half the dose and without a dose claim. A reactor validated to the USEPA guidance manual carries a validated dose at a stated flow and transmittance, in the form a public water system or a health authority reviewing a private supply recognizes, at a cost that reflects the validation. (13.4)
13.5 Where the supply is a private well or any source not disinfected by a water purveyor, the ultraviolet unit shall be certified to NSF/ANSI 55 Class A or validated to the USEPA Ultraviolet Disinfection Guidance Manual.
13.6 The lamp type shall be as indicated in the datasheet.
Ultraviolet Lamp Typeselect
Low-pressure mercury lamp
Low-pressure high-output amalgam lamp
Medium-pressure mercury lamp
NOTE A low-pressure lamp emits almost entirely at the germicidal wavelength and is the most efficient per watt, which suits a small flow; a high-output amalgam lamp emits several times the output from the same lamp length and holds it over a wider water temperature range, which suits a larger flow in a compact reactor; a medium-pressure lamp emits across a broad spectrum at far higher power density, serves the largest flows in the fewest lamps, and consumes more electricity and runs hotter for the same dose. (13.7)
13.8 The ultraviolet unit shall be rated to deliver the certified or validated dose at the design service flow rate and at the ultraviolet transmittance measured in the raw water analysis after the upstream treatment stages.
13.9 The ultraviolet unit shall be furnished with a calibrated intensity sensor, a lamp failure alarm, a low intensity alarm, an elapsed lamp hour meter, and a solenoid valve on the outlet that closes on lamp failure or low intensity.
NOTE Without the solenoid valve a failed lamp simply passes untreated water to the building, with nothing at any outlet to show that it has; the valve is what converts a lamp failure into an outage the building notices rather than an exposure it does not. (13.10)
13.11 The lamp failure and low intensity alarms shall be reported to the monitoring interface specified in this standard.
13.12 The ultraviolet unit shall be preceded by a sediment filter rated at or finer than the unit manufacturer requires, and shall be installed downstream of every other treatment stage.
13.13 The quartz sleeve shall be removable for cleaning without disconnecting piping, and where the unit manufacturer offers a sleeve wiper for the model furnished, the wiper shall be provided.

14 Chemical Feed

14.1 Requirements in this section apply where the datasheet selects chemical feed as a provided stage.
14.2 The chemical feed systems provided shall be as indicated in the datasheet.
Chemical Feed Systemscheckbox
☐ Polyphosphate sequestrant
☐ Orthophosphate or blended phosphate corrosion inhibitor
☐ Alkali feed for pH and alkalinity adjustment
☐ Calcite contactor for pH neutralization
☐ Hypochlorite feed for disinfection of a private supply
☐ Sodium bisulfite feed for dechlorination
☐ Antiscalant ahead of reverse osmosis
14.3 Every chemical fed into the potable supply shall be certified to NSF/ANSI 60 and shall be fed at or below the maximum use level that certification states.
14.4 Each chemical shall be fed by its own metering pump through its own feed line and its own injection quill, with a calibration column on the pump suction, and the pump shall be paced from a water meter so that the dose follows the flow.
NOTE A timer-paced feed doses the same amount whether the building is drawing its peak or nothing at all, which over-doses the night and under-doses the morning; meter pacing is what holds the concentration at the outlet. (14.5)
14.6 Each metering pump shall be interlocked to stop on loss of flow in the line it feeds.
14.7 The injection point of each chemical shall be downstream of the backflow assembly protecting the building supply and shall be protected against backflow of the chemical into the supply as Backflow PreventionBackflow PreventionResolves to the current adopted revision.sync/backflow-prevention requires for a chemical feed connection.
14.8 Chemical storage shall be provided with secondary containment sized for the largest container, located as indicated on the plumbing plans, and with the Safety Data Sheet for each chemical posted at the storage location.
14.9 A calcite contactor shall be a backwashing vessel containing calcium carbonate media certified to NSF/ANSI 60, with a refill port, and the hardness it adds shall be accounted for in the sizing of any softener downstream of it.

15 Bypass, Isolation, and Sampling

15.1 The bypass arrangement for each treatment stage that this standard requires to be bypassable shall be as indicated in the datasheet.
Bypass Arrangementselect
Bypass valve integral to the control valve
Field-piped three-valve bypass with full-port isolation valves
Field-piped three-valve bypass with an automatic bypass valve that opens on fault
NOTE An integral bypass is a lever on the control valve and is the bypass on nearly every small softener; it is sized to the valve and is not full-port. A field-piped three-valve bypass carries the full building flow around the stage with no pressure drop, lets the stage be removed entirely, and is the arrangement on commercial trains. An automatic bypass valve opens the bypass on a controller fault so that the building keeps its water while the stage is down, which matters where the alternative is a building with no water pressure in the middle of the night. (15.2)
15.3 Each softener, each backwashing filter, each reverse osmosis unit, and each ultraviolet unit shall be provided with a bypass so that the building can be served while that stage is out of service.
15.4 Each cartridge and bag housing shall be provided with isolation valves on its inlet and outlet, and with a bypass where the housing is not duplexed.
15.5 Where the datasheet selects a field-piped bypass, the bypass line shall be the full size of the treated water main, and its valves shall be full-port.
15.6 Each bypass valve shall be labeled with its normal position and with the stage it bypasses.
NOTE A bypass left open after a service visit delivers untreated water to the building indefinitely, with the treatment stage running and regenerating as if it were doing its job; the label and the startup verification are what make that visible. (15.7)
15.8 Each stage shall be provided with a union, flange, or grooved coupling on its inlet and on its outlet so that the stage can be removed without cutting piping.
15.9 A sample port with a smooth-nosed, non-threaded outlet shall be provided on the inlet and on the outlet of each treatment stage, positioned so that a sample bottle can be held beneath it.
15.10 A pressure gauge shall be provided on the inlet of the first stage, on the outlet of each stage, and on the outlet of the treatment train.
NOTE Equipment furnished with an integral inlet and outlet gauge satisfies the gauge requirement for that stage. (15.11)
15.12 A test cock or a sample port on the raw water side and on the treated water side of the softener shall be arranged so that a hardness test can be taken while the softener is in service.

16 Drain Connections and Discharge

16.1 Indirect Waste and Air Gap

16.1.1 Every discharge from the treatment equipment, including backwash, brine rinse, concentrate, tank overflow, and vessel drain-down, shall discharge to the drainage system as an indirect waste through an air gap.
16.1.2 No drain, overflow, or concentrate line from the treatment equipment shall be connected directly to the drainage system.
NOTE A direct connection lets drainage back up into the equipment on a stoppage and lets sewer gas enter the treatment train, and the regeneration drain is in contact with the potable side of the control valve during every cycle; the air gap is what makes the drain a one-way path. (16.1.3)
16.1.4 The air gap between the end of each discharge line and the flood level rim of the receptor shall be not less than twice the effective opening of the discharge line, not less than 1 in., and not less than the adopted plumbing code requires for the discharge line size.
16.1.5 Where an air gap fitting is used in place of an open discharge over the receptor, the fitting shall be listed for the purpose and sized for the peak discharge rate of the line it serves.
16.1.6 Each discharge line shall be secured so that the discharge cannot lift out of the receptor under the force of the flow.
16.1.7 The drain line from each control valve shall be not smaller than the drain connection on the valve, shall be a material the adopted plumbing code permits for indirect waste piping and that is unaffected by saturated brine, and shall contain no valve.
16.1.8 The drain line shall not rise above the control valve by more than the height the valve manufacturer publishes, and shall not run longer than the length the manufacturer publishes for the drain connection size.
NOTE A drain line that rises too high or runs too far puts back pressure on the injector, and an injector under back pressure draws brine slowly or not at all; the manufacturer's limits are the limits of the regeneration, not of the pipe. (16.1.9)
16.1.10 The brine tank overflow shall run by gravity to the receptor with no rise and no valve, through its own air gap.
16.1.11 Discharge lines from the treatment equipment shall terminate over the receptors shown on the plumbing plans.

16.2 Backwash and Brine Discharge

16.2.1 The peak drain flow from each vessel shall be as indicated in the datasheet.
Peak Drain Flow per Vesselrange
Not more than
GPM
1235810152030406080100150200300
Derived — the resin or media volume and vessel diameter, and the manufacturer's published backwash rate for the media at the design feedwater temperature (by default)
NOTE The backwash rate per square foot of bed that a media requires is published by its manufacturer, and the vessel diameter sets the area, so the drain flow a vessel produces is arithmetic on those two figures rather than a selection; it is the flow the receptor and the drainage piping downstream of it are sized to receive. (16.2.2)
16.2.3 The Contractor shall confirm that the receptor and the drainage piping furnished under Sanitary Waste And Vent PipingSanitary Waste and Vent PipingResolves to the current adopted revision.sync/sanitary-waste-and-vent-piping accept the peak drain flow of every vessel that can discharge at the same time, and shall report any shortfall before the equipment is ordered.
16.2.4 Where the regeneration of more than one vessel could coincide, the controllers shall be interlocked so that no two vessels discharge at the same time unless the receptor is sized for the combined flow.
NOTE Regeneration brine carries chloride at a concentration far above anything else the building discharges, and sewer authorities that limit chloride at the treatment plant, or that are under a discharge permit for it, treat a softener as a point source; some prohibit on-site regeneration outright. (16.2.5)
16.2.6 The Contractor shall obtain the sewer authority's written confirmation that the regeneration brine and backwash discharge is accepted before the softener is ordered, and shall include it in the informational submittals.
16.2.7 Where the sewer authority conditions its acceptance on a discharge limit, the softener shall be configured to meet that limit by its regeneration arrangement, its salt dose, or its regeneration initiation, as the Engineer of Record directs.
16.2.8 Where any discharge from the treatment equipment is heated, acidic, or alkaline beyond the limits the receiving piping material tolerates, the Contractor shall report the condition before the equipment is ordered.

17 Controls and Monitoring

17.1 Controller and Alarms

17.1.1 Each powered treatment stage shall be furnished with a controller providing a local display of the stage's status, the cycle in progress, the volume treated or capacity remaining where the stage meters it, and any active fault.
17.1.2 The monitoring outputs provided to the building automation system shall be as indicated in the datasheet.
Monitoring Outputscheckbox
☑ Common fault dry contact
☑ Regeneration or backwash in progress dry contact
☑ Brine tank salt low dry contact
☐ Bypass open dry contact
☐ Treated water flow pulse output
☐ Differential pressure high dry contact
☐ Ultraviolet lamp failure or low intensity dry contact
☐ Reverse osmosis permeate quality high dry contact
☐ Network communication to the building automation system
NOTE A softener with an empty brine tank regenerates on schedule, rinses the bed, and returns to service delivering hard water with every indicator normal; the salt low contact is the alarm that catches the failure mode a softener has no other way to report. (17.1.3)
NOTE Where the datasheet selects network communication, the protocol, the point mapping, and the integration are the subject of Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system; this standard furnishes the interface at the equipment. (17.1.4)
17.1.5 Each alarm output shall be a dry contact rated for the control circuit that Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system provides, or a network point where network communication is selected.
17.1.6 Each alarm shall also be annunciated at the controller display and shall latch until acknowledged at the controller.

17.2 Enclosure and Electrical Connection

17.2.1 The enclosure rating of each controller and electrical enclosure shall be as indicated in the datasheet.
Control Enclosure Ratingselect
NEMA Type 1
NEMA Type 3R
NEMA Type 4
NEMA Type 4X
NEMA Type 12
NOTE A dry, conditioned equipment room is the norm and NEMA Type 1 serves it; the harsher locations below call for the higher types regardless of the datasheet selection. (17.2.2)
17.2.3 Where a controller or electrical enclosure is installed outdoors, it shall be rated not less than NEMA Type 3R.
17.2.4 Where a controller or electrical enclosure is installed in a washdown area, a chemical storage area, or a location where brine or chemical spray can reach it, it shall be rated NEMA Type 4X.
17.2.5 Where a controller or electrical enclosure is installed in a location subject to airborne dust or dripping liquid, it shall be rated not less than NEMA Type 12.
17.2.6 The control power supply shall be as indicated in the datasheet.
Control Power Supplyselect
120 V, 1Φ, hard-wired through a disconnecting means
120 V, 1Φ, cord and plug to a dedicated receptacle
24 V from a listed Class 2 transformer on a 120 V receptacle
NOTE A small control valve draws a few watts and ships with a plug-in Class 2 transformer, which is why a cord and plug or a low-voltage connection is the norm below commercial size; a hard-wired connection through a disconnecting means is what a controller with pumps, solenoids, or a stager needs, and it is also the connection that cannot be unplugged by whoever needs the receptacle. (17.2.7)
17.2.8 Each receptacle serving the treatment equipment shall be on a dedicated circuit, located within the cord length the equipment manufacturer provides, and protected by a ground-fault circuit interrupter where NFPA 70 requires it for the location.
17.2.9 Each hard-wired controller, pump, and ultraviolet unit shall be provided with a disconnecting means within sight of the equipment it serves, meeting NFPA 70 for the load.
17.2.10 The Contractor shall report any difference between the nameplate electrical characteristics of the equipment furnished and the scheduled electrical characteristics before rough-in.
17.2.11 Equipment grounding and bonding shall comply with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.
17.2.12 Where a non-metallic vessel, valve body, or bypass interrupts the metallic path of the piping at the equipment, a bonding jumper shall be installed across it so that the piping on both sides of the equipment remains electrically continuous.

18 Installation

18.1 Equipment Placement and Anchorage

18.1.1 Each vessel shall be set level on a housekeeping pad or on the base the vessel manufacturer furnishes, in the location shown on the plumbing plans.
18.1.2 Clearance shall be maintained around each vessel for resin and media replacement, around each control valve for its removal, above each cartridge and bag housing for the cartridge length plus the withdrawal allowance the housing manufacturer publishes, above each ultraviolet unit for the lamp and sleeve length plus the withdrawal allowance, and in front of each brine tank for salt loading.
18.1.3 The equipment shall be set so that the largest single component requiring replacement can be removed from the room without dismantling permanent building construction.
18.1.4 Seismic anchorage of the vessels, brine tanks, storage tanks, and skids shall be as indicated in the datasheet.
Seismic Anchorageselect
None required
Anchorage to a pre-approved detail listed for the vessel
Anchorage designed by a registered design professional
Derived — Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category and the component importance factor the project assigns to the domestic water service (by default)
18.1.5 Where anchorage is required, it shall be designed in accordance with ASCE 7 for the operating weight of the vessel full of media and water, and shall be installed before the vessel is filled.
NOTE A composite vessel is anchored at its base and restrained at its upper third rather than clamped tightly around its shell, because the shell flexes under pressure and a rigid band cuts into the winding. (18.1.6)
18.1.7 Where a composite vessel is restrained, the restraint shall be of the type the vessel manufacturer publishes for the vessel and shall not clamp the shell.

18.2 Piping Connections at the Equipment

18.2.1 Piping shall be supported independently of the equipment so that no piping weight or thermal movement is carried by a control valve, a housing, or a vessel connection.
18.2.2 The inlet and outlet of each stage shall be connected so that flow passes through the stage in the direction marked on it.
NOTE A softener piped backward passes raw water up through the drain path and backwashes on service; it is the single most common startup fault, and it is caught by reading the arrow on the valve before the union is made up. (18.2.3)
18.2.4 Transitions between the equipment connection material and the piping material shall be made with fittings listed for that combination, and dielectric separation shall be provided where Domestic Water PipingDomestic Water PipingResolves to the current adopted revision.sync/domestic-water-piping requires it for the materials joined.
18.2.5 Flexible connectors, where used at the equipment, shall be certified to NSF/ANSI/CAN 61, rated for the system pressure and temperature, and installed without twist or offset.
18.2.6 No piping, drain line, or brine line shall be routed where it blocks access to a control valve, a housing cover, a brine tank lid, or a vessel loading port.

18.3 Identification

18.3.1 Each vessel, control valve, housing, brine tank, storage tank, ultraviolet unit, chemical feed pump, and isolation and bypass valve shall carry a permanent tag giving the equipment identifier from the schedule, the service, and the normal valve position where the item is a valve.
18.3.2 Tag numbering shall match the as-built piping schematic so that any tagged device can be located from the schematic and any device in the field can be found on it.
18.3.3 A permanent placard at the treatment train shall state the stages provided, the treatment objective of each, the direction of flow through the train, and the bypass valve positions for normal service and for bypass.
18.3.4 Pipe and valve identification shall comply with Plumbing Piping IdentificationPlumbing Piping IdentificationResolves to the current adopted revision.sync/plumbing-piping-identification.

19 Startup and Field Testing

19.1 Protection During System Disinfection

NOTE The chlorination of new potable piping under Disinfection Of Water SystemsDisinfection of Domestic Water SystemsResolves to the current adopted revision.sync/disinfection-of-water-systems uses chlorine at concentrations far above a supply residual, and that water passed through a resin bed, a carbon bed, a membrane, or a lamp sleeve damages each in a single contact; the equipment is therefore kept out of the chlorinated water, and the sections of piping it occupies are disinfected around it. (19.1.1)
19.1.2 Before chlorinated water is introduced for the disinfection of the distribution piping, the Contractor shall isolate every softener, carbon filter, iron and manganese filter, reverse osmosis unit, and ultraviolet unit by closing its isolation valves and opening its bypass, or shall physically disconnect it.
19.1.3 The Contractor shall confirm by a free chlorine test at the inlet sample port of each isolated stage, taken during the contact period, that chlorinated water has not reached the stage.
19.1.4 Where chlorinated water is found to have reached a stage, the Contractor shall replace the resin, media, membranes, or sleeve seals of that stage at the Contractor's cost unless the manufacturer confirms in writing that the exposure did not damage them.
19.1.5 After the distribution piping has been flushed, and after the free chlorine residual at the inlet sample port has returned to the supply's normal residual, the Contractor shall return each stage to service in the order of flow.
19.1.6 The piping between the bypass valves and each isolated stage, which the system chlorination did not reach, shall be disinfected by the sanitizing procedure the equipment manufacturer publishes for the stage, carried out as part of startup.
NOTE The disinfection procedure, the contact time, and the bacteriological clearance of the piping are the subject of Disinfection Of Water SystemsDisinfection of Domestic Water SystemsResolves to the current adopted revision.sync/disinfection-of-water-systems; this standard governs what is done to protect the equipment and to sanitize the sections that procedure bypasses. (19.1.7)

19.2 Media Loading and Startup

19.2.1 Resin and media shall be loaded into each vessel through the loading port with the vessel partly filled with water, and the distributor shall be protected from the falling media during loading.
19.2.2 Each softener shall be sanitized at startup by the resin manufacturer's published procedure, and the sanitizing solution shall be rinsed to the drain before the softener is placed in service.
19.2.3 Each softener shall be put through a complete manual regeneration at startup, during which the Contractor shall observe and record that the backwash rate matches the published rate, that brine is drawn at the expected rate and for the expected duration, that the brine tank refills to its set level and the refill stops, and that the drain line and overflow discharge through their air gaps without overflow or leakage.
19.2.4 Each backwashing filter shall be backwashed to a clear discharge before it is placed in service.
19.2.5 Each granular carbon vessel shall be backwashed to remove fines and shall be rinsed until the outlet runs clear before it is placed in service.
19.2.6 Each ultraviolet unit shall be started with the lamp energized for the warm-up period the manufacturer publishes before water is passed to the building, and the intensity sensor reading at startup shall be recorded as the reference against which lamp aging is judged.
19.2.7 Each reverse osmosis unit shall be started by the membrane manufacturer's published procedure, with the preservative rinsed to drain and the permeate diverted to drain until its conductivity is within the limit the manufacturer publishes.
19.2.8 The Contractor shall set every controller to the settings indicated in the datasheet and in the reviewed sizing calculation, and shall record each setting as left in the startup report.
19.2.9 The Contractor shall verify at the end of startup that every bypass valve is in its normal service position and that every isolation valve is open.

19.3 Field Performance Test

19.3.1 The field performance test shall be conducted after startup, with the building water system filled and disinfected and with the treatment train in normal service.
19.3.2 The field performance test shall verify the items indicated in the datasheet.
Field Performance Test Documentationcheckbox
☐ Raw and treated water hardness at design flow
☐ Treated water hardness at the end of a service run
☐ Free chlorine or chloramine across the carbon stage
☐ Iron and manganese across the removal stage
☐ Pressure drop across each stage at design flow
☐ Observed regeneration cycle and drain discharge
☐ Salt consumption per regeneration against the design dose
☐ Reverse osmosis permeate quality, permeate rate, and recovery
☐ Ultraviolet intensity sensor reading and solenoid closure on simulated lamp failure
☐ Chemical feed dose at the injection point against the design dose
☐ Alarm and monitoring point verification at the building automation system
19.3.3 The field performance test shall verify that the treated water hardness at the design service flow rate is at or below the treated water hardness limit indicated in the datasheet, by a hardness test on a sample from the softener outlet sample port.
19.3.4 Where the datasheet selects blending, the hardness test shall be taken downstream of the blending point and shall verify the hardness the Engineer of Record directed.
19.3.5 The field performance test shall verify that the pressure drop across each stage at the design service flow rate does not exceed the limit this standard sets for the stage.
19.3.6 The field performance test shall verify that each alarm indicated in the datasheet reaches the building automation system by simulating the condition at the equipment.
19.3.7 Where the datasheet selects an ultraviolet unit, the field performance test shall verify that the outlet solenoid closes on a simulated lamp failure.
19.3.8 Where a test result falls outside a specified value, the Contractor shall correct the cause and retest at no cost to the Owner.
19.3.9 Where the parties disagree whether an observed condition constitutes a failed result, the Engineer of Record shall make the initial determination.
NOTE Commissioning activities beyond this test are the subject of CommissioningTotal Building CommissioningResolves to the current adopted revision.sync/commissioning. (19.3.10)

20 Delivery, Storage, and Handling

20.1 Equipment shall be delivered in the manufacturer's packaging with factory covers, plugs, and tags in place, and the Contractor shall inspect each item for shipping damage on arrival at the site.
20.2 The Contractor shall report shipping damage in writing to the carrier and to the equipment manufacturer before the damaged item is installed.
20.3 Damaged equipment shall not be installed until the manufacturer confirms in writing that the damage does not affect its performance, certification, or warranty.
20.4 Resin and media shall be delivered in the manufacturer's sealed packaging and stored indoors, above freezing, out of direct sunlight, and off the floor until they are loaded.
NOTE Resin ships moist and the water in each bead freezes and fractures it, so a pallet of resin left on a loading dock through a cold night arrives at the vessel as a pallet of fines. (20.5)
20.6 Reverse osmosis membrane elements shall be stored in their sealed bags, within the temperature range the membrane manufacturer publishes, and shall not be allowed to dry out.
20.7 Ultraviolet lamps and quartz sleeves shall be stored in their packaging and handled only with the gloves the manufacturer supplies.
20.8 Regeneration salt shall be stored dry, off the floor, and protected from contamination, and shall be a water softener grade salt the softener manufacturer accepts.
NOTE Rock salt carries insoluble grit that accumulates in the brine tank and fouls the injector, which is why the softener manufacturer names the grades the tank accepts. (20.9)
20.10 Open vessel, valve, and piping connections shall be capped until the connection is made.
20.11 Vessels shall be stored upright, shall not be stacked, and shall be protected from impact to the shell.

21 Warranty

21.1 The Contractor shall procure equipment carrying at least the warranty coverage indicated in the datasheet.
21.2 The Contractor shall furnish evidence of that coverage in the closeout submittals.
Warranty Period — Control Valves and Controllersrange
Not less than
yr
1235710
Warranty Period — Pressure Vessels and Tanksrange
Not less than
yr
135710152025
21.3 Where the datasheet indicates no warranty period, the equipment shall carry the standard published warranty for its class.
21.4 Where the equipment carries the standard published warranty, the Contractor shall state that period in the closeout submittals.
21.5 Resin, filter media, cartridges, membranes, and lamps shall carry the manufacturer's published warranty against defects, and the Contractor shall state the published life or prorating basis of each in the closeout submittals.
21.6 The warranty period shall begin at substantial completion or at the date of beneficial use by the Owner, whichever is earlier.
21.7 Where a warranted component is repaired or replaced, the repaired or replaced component shall carry a fresh full warranty term running from the date of the repair, or the remainder of the original term, whichever ends later.
21.8 The Contractor shall bear the cost of removing and reinstalling adjacent work required to reach a component being repaired under warranty.
21.9 The Contractor shall record the condition of that adjacent work before it is disturbed and shall restore it to the recorded condition.
21.10 Warranty coverage shall not be voided by water quality within the limits the equipment manufacturer publishes.
21.11 Where the Owner requires the equipment to operate on water outside those published limits, the Owner and the Engineer of Record shall record that condition and the treatment provided in the contract documents.

22 Spare Parts

22.1 The Contractor shall deliver the spare parts indicated in the datasheet to the Owner at substantial completion, each marked with the identifier of the equipment it serves and stored together in a labeled container in the equipment room or in a location the Owner designates.
  • one complete set of replacement sediment cartridges or bags for each housing
  • one complete set of replacement carbon block cartridges for each carbon housing
  • one seal and spacer kit, or the equivalent rebuild kit, for each control valve model
  • one brine injector assembly for each injector size furnished
  • one float valve assembly for each brine tank model
  • one ultraviolet lamp and one quartz sleeve, with sleeve seals, for each ultraviolet unit
  • one set of membrane elements for each reverse osmosis unit, where the Owner elects it
  • one diaphragm or tube kit for each chemical metering pump model
  • an initial charge of regeneration salt sufficient for the days of storage indicated in the datasheet
Spare Parts Deliverycheckbox
☐ Sediment cartridges or bags
☐ Carbon block cartridges
☐ Control valve rebuild kits
☐ Brine injector assemblies
☐ Brine tank float valve assemblies
☐ Ultraviolet lamps and sleeves
☐ Reverse osmosis membrane elements
☐ Metering pump diaphragm or tube kits
☐ Initial regeneration salt charge
22.2 The Contractor shall obtain the Owner's signed receipt for the spare parts delivered.

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"Domestic Water Softeners and Filtration," SynC Standards, revision 4. Licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://synergyinconstruction.com/standards/general/domestic-water-softeners-and-filtration. Reference material only; not professional engineering advice and provided without warranty. Verify against governing codes and have a licensed professional review before use.