+---
+title: Domestic Water Softeners and Filtration
+category: Plumbing
+toc_depth: 3
+description: >
+ When to use: Point-of-entry (POE) treatment of the domestic cold-water supply entering a building before distribution, in commercial, institutional, multifamily residential, and light-industrial projects where incoming municipal or well water hardness, sediment, chlorine, taste/odor, or other quality parameters must be mitigated to protect downstream plumbing, water heaters, and hydronic equipment or to satisfy code and warranty requirements. Covers cation-exchange softeners, multimedia and cartridge sediment filters, granular activated carbon (GAC) filters, point-of-entry reverse-osmosis skids, salt-free scale conditioners, UV disinfection, and combination treatment trains, including selection, sizing, pre- and post-filtration, brine/backwash discharge, bypass provisions, sampling ports, controls, and commissioning.
+
+ Not intended for: Central HVAC/chilled-water and boiler/cooling-tower chemical water treatment (see [[sync/hvac-water-treatment]]); domestic distribution piping downstream of the treatment equipment (see [[sync/domestic-water-piping]]); pressure-boosting equipment for the domestic system (see [[sync/domestic-water-booster-pumps]]); water heaters and storage tanks (see [[sync/water-heaters]]); backflow prevention devices at the point of connection (see [[sync/backflow-prevention]]); sanitary drainage and interceptors receiving the brine/backwash discharge (see [[sync/grease-interceptors]]); plumbing insulation on treatment piping (see [[sync/plumbing-insulation]]); and industrial process water, ultrapure water, and cooling-tower makeup conditioning.
+---
+
+# Scope {toc}
+
+## This standard covers the selection, sizing, construction, controls, installation, and commissioning of point-of-entry water treatment equipment that conditions the domestic cold-water supply before it is distributed through the building. {note}
+
+## Covered equipment includes the following equipment types, used singly or assembled into a combination treatment train: {note}
+
+- Cation-exchange water softeners regenerated with sodium chloride or potassium chloride.
+- Multimedia pressure filters for sediment and turbidity reduction.
+- Cartridge sediment filters in single or manifolded housings.
+- Granular activated carbon (GAC) filters for chlorine, taste, and odor reduction.
+- Point-of-entry reverse-osmosis (RO) skids for total-dissolved-solids (TDS) reduction.
+- Salt-free scale conditioners (template-assisted crystallization and polyphosphate feeders).
+- Ultraviolet (UV) disinfection units used as a final stage on well-water trains.
+
+## The work extends from the cold-water service connection downstream of the building's backflow protection, through the treatment equipment, its bypass, its brine and backwash drain connections, and its controls, to the conditioned-water connection feeding the building domestic distribution. {note}
+
+## The incoming backflow assembly at the point of connection, the conditioned-water distribution piping, the domestic booster pumps, and the water heaters are each governed by their own standard and are coordinated with, but not specified by, this standard. {note}
+
+## Process water, cooling-tower makeup, boiler feedwater, and ultrapure/laboratory water systems are excluded; treatment of those systems is governed by [[sync/hvac-water-treatment]] and the applicable process discipline. {note}
+
+# Treatment Objective {toc}
+
+## The treatment objective is the first decision the design must resolve, because it determines equipment type, certification basis, and whether the system removes a contaminant or merely conditions the water. {note}
+
+## Softening removes hardness ions (calcium and magnesium) by ion exchange; sediment filtration removes turbidity and particulates; carbon filtration reduces chlorine, taste, and odor; RO reduces dissolved solids; and scale conditioning inhibits scale crystallization without removing any ion. These outcomes are not interchangeable. {note}
+
+## The treatment objective shall be stated explicitly in the Contract Documents so that a scale-conditioning device is not substituted where actual hardness-ion removal is required for code compliance or equipment warranty.
+
+## Where downstream water heaters or hydronic equipment carry a warranty conditioned on softened water, the system shall remove hardness ions to the maximum hardness limit stated in that warranty rather than merely inhibiting scale.
+
+```datasheet
+label: Primary Treatment Objective
+type: checkbox
+options:
+ - Hardness removal (softening)
+ - Sediment / turbidity removal
+ - Chlorine, taste, and odor reduction
+ - Health-contaminant reduction (lead, cysts, VOCs, nitrate, arsenic)
+ - TDS reduction (reverse osmosis)
+ - Microbiological disinfection (UV)
+ - Scale inhibition without hardness removal
+default:
+ - Hardness removal (softening)
+```
+
+# Referenced Standards {toc}
+
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a different edition is enforced by the authority having jurisdiction.
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| NSF/ANSI 44-2024 | Residential Cation Exchange Water Softeners |
+| NSF/ANSI/CAN 61-2025 | Drinking Water System Components — Health Effects |
+| NSF/ANSI 42 | Drinking Water Treatment Units — Aesthetic Effects |
+| NSF/ANSI 53 | Drinking Water Treatment Units — Health Effects |
+| NSF/ANSI 58 | Reverse Osmosis Drinking Water Treatment Systems |
+| NSF/ANSI 55 | Ultraviolet Microbiological Water Treatment Systems |
+| NSF/ANSI 372 | Drinking Water System Components — Lead Content |
+| 2021 IPC | International Plumbing Code, Chapter 6 — Water Supply and Distribution |
+| 2021 UPC | Uniform Plumbing Code, Chapter 6 — Water Supply and Distribution |
+| WQA S-100 | Water Quality Association Standard for Softeners |
+| ASTM D2473 | Styrene-Divinylbenzene Cation Exchange Resin |
+
+## The NSF/ANSI 44 scope is nominally limited to residential cation-exchange softeners, but the standard is universally applied to commercial submittals and commercial-scale units are certified to it in practice; certification to NSF/ANSI 44 is therefore required for cation-exchange softeners regardless of project scale. {note}
+
+# Submittals {toc}
+
+## The Contractor shall submit the following Action Submittals for review before fabrication or ordering:
+
+- Product data for each treatment unit, including rated capacity, service flow rate, pressure drop curve, and connection sizes.
+- Certification listings confirming NSF/ANSI compliance for each unit and each wetted component (NSF/ANSI 44, 42, 53, 58, 55, 61, and 372 as applicable).
+- Sizing calculations showing incoming hardness, daily demand, grains-per-day load, selected salt dose, and resulting regeneration frequency.
+- Brine and backwash discharge calculations, including peak backwash flow and required air-gap dimension.
+- Control sequence and BMS interface point list, including salt-low alarm, fault, and flow-meter pulse output.
+- Wiring diagram and electrical load for each electronic control head.
+
+```datasheet
+label: Action Submittals
+type: checkbox
+options:
+ - Product data for each treatment unit
+ - NSF/ANSI certification listings (wetted components)
+ - Sizing calculations (hardness, demand, salt dose, regen frequency)
+ - Brine / backwash discharge and air-gap calculations
+ - Control sequence and BMS point list
+ - Wiring diagram and electrical load data
+default:
+ - Product data for each treatment unit
+ - NSF/ANSI certification listings (wetted components)
+ - Sizing calculations (hardness, demand, salt dose, regen frequency)
+ - Brine / backwash discharge and air-gap calculations
+```
+
+## The Contractor shall submit the following Closeout Submittals before Substantial Completion:
+
+- Operation and maintenance manuals for each unit, including regeneration setup, media replacement intervals, and salt specification.
+- A media and cartridge replacement protocol identifying spent-carbon handling and change-out frequency.
+- Commissioning report documenting hardness, chlorine, and pressure-drop test results before and after treatment.
+- Warranty documents for resin, media, control valves, and electronic heads.
+
+```datasheet
+label: Closeout Submittals
+type: checkbox
+options:
+ - Operation and maintenance manuals
+ - Media and cartridge replacement protocol
+ - Commissioning report (before/after water quality)
+ - Warranty documents
+default:
+ - Operation and maintenance manuals
+ - Media and cartridge replacement protocol
+ - Commissioning report (before/after water quality)
+ - Warranty documents
+```
+
+## The Contractor shall submit the following Informational Submittals:
+
+- An on-site or laboratory water-quality analysis of the incoming supply used as the sizing basis.
+- The local sewer authority discharge limits or permit applicable to regeneration brine, where chloride discharge is restricted.
+
+```datasheet
+label: Informational Submittals
+type: checkbox
+options:
+ - Incoming water-quality analysis (sizing basis)
+ - Brine discharge limits / municipal permit documentation
+default:
+ - Incoming water-quality analysis (sizing basis)
+```
+
+# Quality Assurance {toc}
+
+## All wetted components in potable service — resin, filter media, valve bodies, tanks, and fittings — shall be certified to NSF/ANSI/CAN 61 for health effects.
+
+## Components in potable service shall comply with NSF/ANSI/CAN 61 for chemical leaching.
+
+## Wetted metallic components shall comply with the lead-content limits of NSF/ANSI 372.
+
+## Cation-exchange softeners shall be certified to NSF/ANSI 44.
+
+## Carbon and sediment filters specified for aesthetic reduction shall be certified to NSF/ANSI 42.
+
+## Filters specified for health-contaminant reduction shall be certified to NSF/ANSI 53.
+
+## Reverse-osmosis units shall be certified to NSF/ANSI 58.
+
+## Ultraviolet disinfection units shall be certified to NSF/ANSI 55.
+
+## Ion-exchange resin shall be styrene-divinylbenzene cation-exchange resin conforming to ASTM D2473.
+
+## NSF/ANSI 44 rated grain capacities are established at the maximum salt dose; a unit's catalog capacity is therefore not the capacity it will deliver at an efficient salt dose, and the two must not be confused during selection. {note}
+
+# Environmental and Service Conditions {toc}
+
+## Ion-exchange resin and filter media are temperature-sensitive and freeze-intolerant, which constrains where the equipment may be installed and which line it may serve. {note}
+
+## Treatment equipment shall be installed on the cold-water supply only, upstream of all water heaters and hydronic heat sources.
+
+## Treatment equipment shall not be installed on a hot-water line or downstream of a water heater, because cation-exchange resin degrades above 110°F (43°C) and softening performance is lost.
+
+## Equipment shall be located in a conditioned space; where freezing is possible, a heat-traced and insulated enclosure shall be provided, because resin tanks and valve assemblies are not freeze-tolerant.
+
+## The equipment shall be sized and rated for the service conditions in the datasheet below.
+
+```datasheet
+label: Service Conditions
+type: range
+unit: psi
+min: 20
+max: 125
+step: 5
+setpoints:
+ - 20
+ - 60
+ - 125
+default: 60
+```
+
+```datasheet
+label: Operating Water Temperature Range
+type: select
+options:
+ - 40-100°F (4-38°C) — standard resin/media service
+ - 40-80°F (4-27°C) — cold-climate well supply
+default: 40-100°F (4-38°C) — standard resin/media service
+```
+
+## The equipment shall be located within reach of a gravity-accessible floor drain sized for backwash surge flow, and within 6 ft (1.8 m) of a dedicated 120 VAC receptacle or junction box for the electronic control head.
+
+# Softener Selection and Configuration {toc}
+
+## Softener configuration is governed by three coupled decisions — softener chemistry, single versus twin tank, and regeneration control — each of which is set independently by the application. {note}
+
+## Softener chemistry shall be selected to match the treatment objective: sodium-chloride cation exchange for general hardness removal, potassium-chloride cation exchange where low-sodium effluent is required, and salt-free conditioning only where scale inhibition without ion removal is acceptable.
+
+## Potassium-chloride regeneration shall be specified where sodium-sensitive occupants or processes — dialysis, certain food production — require reduced sodium in the effluent.
+
+## Salt-free template-assisted crystallization (TAC) and polyphosphate conditioners do not remove hardness ions and cannot be certified to NSF/ANSI 44; they shall not be substituted where the Contract Documents require hardness-ion removal.
+
+```datasheet
+label: Softener Chemistry
+type: radio
+options:
+ - Sodium-chloride cation exchange
+ - Potassium-chloride cation exchange (low-sodium effluent)
+ - Salt-free TAC (scale inhibition only)
+ - Polyphosphate feeder (scale inhibition only)
+default: Sodium-chloride cation exchange
+```
+
+## A single-tank softener is offline during regeneration and delivers hard water through the bypass during that interval; a twin/duplex alternating system keeps one tank in service while the other regenerates and therefore delivers continuous soft water. {note}
+
+## Facilities requiring continuous soft water — 24/7 healthcare, food service, and hospitality — shall be served by a twin/duplex alternating softener or a hard-water bypass arrangement that maintains service during regeneration and maintenance.
+
+```datasheet
+label: Tank Configuration
+type: radio
+options:
+ - Single tank (regenerates offline)
+ - Twin / duplex alternating (continuous soft water)
+default: Single tank (regenerates offline)
+```
+
+## Regeneration control determines when the unit regenerates: a time-clock regenerates on a fixed calendar regardless of use, while a demand-initiated meter regenerates only after a measured volume has been treated, matching salt and water use to actual demand. {note}
+
+## Commercial and institutional softeners shall use demand-initiated (meter-initiated) regeneration control; time-clock (calendar) control shall not be used for any facility with variable occupancy.
+
+```datasheet
+label: Regeneration Control
+type: radio
+options:
+ - Demand-initiated (metered)
+ - Hardness-sensor-triggered
+ - Time-clock (residential only)
+default: Demand-initiated (metered)
+```
+
+# Softener Sizing and Salt Efficiency {toc}
+
+## Softener sizing reconciles three quantities — the hardness load, the salt dose, and the regeneration frequency — and the most common sizing error is to select on catalog capacity without resolving the salt-dose efficiency trade-off. {note}
+
+## Incoming hardness shall be established from a current water-quality analysis and stated in grains per gallon (gpg), where 1 gpg equals 17.1 mg/L as CaCO3.
+
+## The softener shall be sized so that the grains-per-day load — incoming hardness in gpg multiplied by daily demand in gallons — does not require regeneration more frequently than every three days, with a commercial design target of approximately seven days between regenerations at an efficient salt dose.
+
+## Salt dose is the trade-off between efficiency and capacity: 6 to 8 lbs/ft³ of resin yields roughly 2,000 to 2,500 grains removed per pound of salt, while 15 lbs/ft³ reaches the catalog rated capacity at roughly 3,200 grains per pound but with sharply diminishing efficiency above 8 lbs/ft³. {note}
+
+## The design salt dose shall be 6 to 8 lbs/ft³ of resin for efficient operation unless a specific application justifies a higher dose.
+
+## The salt dose shall not exceed 15 lbs/ft³ of resin.
+
+## Capacity selected against an NSF/ANSI 44 rated capacity shall be derated by 35% to 40% to reflect efficient salt-dose operation when comparing units.
+
+```datasheet
+label: Incoming Hardness
+type: range
+unit: gpg
+min: 3
+max: 25
+step: 1
+setpoints:
+ - 3
+ - 10
+ - 14
+ - 25
+default: 10
+```
+
+```datasheet
+label: Design Salt Dose
+type: range
+unit: lbs/ft³
+min: 6
+max: 15
+step: 1
+setpoints:
+ - 6
+ - 8
+ - 15
+default: 6
+```
+
+```datasheet
+label: Rated Grain Capacity (per tank)
+type: select
+options:
+ - 24,000 grains
+ - 32,000 grains
+ - 48,000 grains
+ - 64,000 grains
+ - 96,000 grains
+ - 120,000 grains
+ - 150,000 grains
+default: 64,000 grains
+```
+
+## The softener shall be sized for the peak instantaneous service flow, and the pressure drop across the softener shall not exceed 15 psi at the design service flow.
+
+```datasheet
+label: Design Service Flow Rate
+type: range
+unit: GPM
+min: 5
+max: 80
+step: 5
+setpoints:
+ - 10
+ - 20
+ - 40
+ - 80
+default: 20
+```
+
+## The brine tank shall hold at least a 30-day supply of salt between fills at the design regeneration frequency.
+
+```datasheet
+label: Brine Tank Salt Storage Capacity
+type: range
+unit: lbs
+min: 200
+max: 500
+step: 50
+setpoints:
+ - 200
+ - 300
+ - 500
+default: 300
+```
+
+# Pre-Filtration and Post-Treatment {toc}
+
+## Pre-filtration protects the resin bed, and post-treatment adds the carbon, RO, or UV stages required by the treatment objective; both are arranged in series with the softener in a defined order. {note}
+
+## A sediment pre-filter rated at 5 µm or finer shall be installed upstream of the softener resin bed to prevent turbidity and iron from fouling the resin and voiding the warranty.
+
+## The sediment pre-filter shall be replaced per the manufacturer's schedule or when the differential pressure across it exceeds 15 psi, whichever occurs first.
+
+```datasheet
+label: Sediment Pre-Filter
+type: radio
+options:
+ - Cartridge, 5 µm, 10-inch housing
+ - Cartridge, 5 µm, 20-inch housing
+ - Cartridge, 1 µm, 20-inch housing
+ - Multimedia pressure filter (sand/anthracite/garnet)
+default: Cartridge, 5 µm, 20-inch housing
+```
+
+## Where chlorine, taste, or odor reduction is required, a granular activated carbon (GAC) filter shall provide a minimum empty-bed contact time (EBCT) of 5 minutes at the rated flow.
+
+## Granular activated carbon can harbor bacteria once exhausted; the Contract Documents shall establish a media change-out interval, and spent carbon shall be handled per the O&M protocol.
+
+```datasheet
+label: Post-Treatment Stages
+type: checkbox
+options:
+ - GAC carbon filter (chlorine / taste / odor)
+ - Reverse-osmosis skid (TDS reduction)
+ - UV disinfection (well water)
+ - None
+default:
+ - GAC carbon filter (chlorine / taste / odor)
+```
+
+## Where TDS reduction is required at point of entry, a reverse-osmosis skid certified to NSF/ANSI 58 shall be provided with a permeate storage tank and repressurization.
+
+## Point-of-entry RO shall be specified only for very high TDS or special-use applications.
+
+## Point-of-use RO is preferred for isolated demands. {note}
+
+## Where well water requires microbiological treatment, a UV disinfection unit certified to NSF/ANSI 55 shall be provided as the final stage at a minimum dose of 30 mJ/cm² at the rated flow.
+
+```datasheet
+label: UV Disinfection Dose
+type: range
+unit: mJ/cm²
+min: 16
+max: 40
+step: 2
+setpoints:
+ - 16
+ - 30
+ - 40
+default: 30
+```
+
+# Bypass, Connections, and Sampling {toc}
+
+## A maintainable treatment system requires an accessible bypass, correctly sized connections, and sampling ports that let the commissioning agent and operator verify performance. {note}
+
+## A full-port bypass shall be provided — factory-integrated three-valve bypass or field-installed full-port ball valves — so that the equipment can be isolated and the building served while a unit is out of service.
+
+## The bypass and service valves shall be accessible per IPC Section 605.4 service-access requirements, and the bypass shall be labeled.
+
+## Sampling ports shall be provided immediately upstream and downstream of each treatment stage to permit verification of treatment performance.
+
+```datasheet
+label: Bypass Configuration
+type: radio
+options:
+ - Factory-integrated three-valve bypass
+ - Field-installed full-port ball valve bypass
+default: Factory-integrated three-valve bypass
+```
+
+```datasheet
+label: Inlet / Outlet Connection Size
+type: select
+options:
+ - 3/4 inch FNPT
+ - 1 inch FNPT
+ - 1-1/2 inch FNPT
+ - 2 inch FNPT
+ - 2-1/2 inch flanged
+ - 3 inch flanged
+default: 1-1/2 inch FNPT
+```
+
+## A backflow preventer shall be provided on the supply upstream of the treatment equipment; the assembly type and location are specified in [[sync/backflow-prevention]].
+
+## The backflow prevention assembly is governed by [[sync/backflow-prevention]] and is not specified here to avoid double-specification. {note}
+
+# Brine and Backwash Discharge {toc}
+
+## The brine and backwash discharge is both a code item and a coordination item: it must be drained through an air gap, sized for backwash surge, and reconciled with local limits on chloride discharge. {note}
+
+## The brine and backwash drain connection shall discharge through an air gap to the receiving drain in accordance with IPC/UPC Table 603.3.1; a direct connection to the drainage system is prohibited.
+
+## The air gap shall be at least twice the drain pipe diameter, and not less than the minimum required by Table 603.3.1; a 1-inch drain therefore requires a minimum 2-inch air gap.
+
+## The backwash drain line shall be sized for the peak backwash flow, which can reach approximately 5 GPM per ft³ of resin, and the receiving floor drain shall be verified to accept that surge.
+
+```datasheet
+label: Brine / Backwash Air-Gap Dimension
+type: range
+unit: in
+min: 1
+max: 4
+step: 0.5
+setpoints:
+ - 1
+ - 2
+ - 4
+default: 2
+```
+
+```datasheet
+label: Receiving Floor Drain Size
+type: select
+options:
+ - 2 inch
+ - 3 inch
+ - 4 inch
+default: 3 inch
+```
+
+## Regeneration brine can carry 50,000 to 100,000 mg/L of chloride, and some municipalities restrict chloride discharge to the sanitary sewer. {note}
+
+## The Contractor shall verify the local sewer authority's chloride discharge limits and obtain any required discharge permit before regeneration is placed in service.
+
+## The drain, brine-tank overflow, and floor drain locations shall be coordinated with the sanitary drainage design.
+
+## The receiving interceptor and drainage are governed by [[sync/grease-interceptors]] and the project plumbing drawings. {note}
+
+## The brine and backwash discharge shall terminate over the floor drain shown on the drawings. [[drawing: mechanical room floor drain]]
+
+# Controls and Monitoring {toc}
+
+## Commercial treatment systems are monitored points on the building management system, and omitting the integration outputs is a common source of RFIs late in the project. {note}
+
+## Each electronic control head shall provide a local display of service status, remaining capacity, and fault condition.
+
+## The softener controller shall provide a hardwired salt-low alarm output and a general fault output to the building management system.
+
+## The softener controller shall provide a flow-meter pulse output for water-use reporting.
+
+```datasheet
+label: Controls and Monitoring Outputs
+type: checkbox
+options:
+ - Local display (status / capacity / fault)
+ - BMS salt-low alarm (hardwired)
+ - BMS general fault (hardwired)
+ - Flow-meter pulse output
+ - Hardness-sensor output
+default:
+ - Local display (status / capacity / fault)
+ - BMS salt-low alarm (hardwired)
+ - BMS general fault (hardwired)
+ - Flow-meter pulse output
+```
+
+## The control head shall be powered from 120 VAC, 60 Hz.
+
+## Remote monitoring connections requiring 24 VDC or a LAN connection shall be coordinated with the electrical and controls work.
+
+```datasheet
+label: Electrical Supply
+type: select
+options:
+ - 120 VAC, 60 Hz, 1Φ
+ - 120 VAC head + 24 VDC monitoring
+ - 120 VAC head + LAN connection
+default: 120 VAC, 60 Hz, 1Φ
+```
+
+# Materials {toc}
+
+## Treatment-equipment materials are constrained by potable-water certification and by the mechanical service of each component. {note}
+
+## Resin tanks shall be fiberglass-reinforced or polyethylene-lined pressure vessels rated for the service pressure and certified to NSF/ANSI/CAN 61.
+
+## Brine tanks shall be high-density polyethylene with a salt platform or brine-well as applicable.
+
+## Control valve bodies shall be lead-free brass or engineered polymer certified to NSF/ANSI/CAN 61 and NSF/ANSI 372.
+
+## Ion-exchange resin shall be styrene-divinylbenzene cation-exchange resin conforming to ASTM D2473 and certified to NSF/ANSI/CAN 61.
+
+```datasheet
+label: Resin Tank Material
+type: radio
+options:
+ - Fiberglass-reinforced composite
+ - Polyethylene-lined steel
+default: Fiberglass-reinforced composite
+```
+
+```datasheet
+label: Control Valve Body Material
+type: radio
+options:
+ - Lead-free brass (NSF 61 / 372)
+ - Engineered polymer (NSF 61)
+default: Engineered polymer (NSF 61)
+```
+
+# Testing and Commissioning {toc}
+
+## Commissioning proves the treatment objective was met by measuring water quality before and after treatment, not merely by confirming the equipment runs. {note}
+
+## The Contractor shall measure and record incoming and treated hardness; treated hardness shall meet the design target and any limit imposed by a downstream equipment warranty.
+
+## Where carbon filtration is provided, the Contractor shall measure and record free-chlorine reduction across the carbon stage at the rated flow.
+
+## The Contractor shall record the pressure drop across each treatment stage at the design flow and confirm it is within the specified limit.
+
+## A regeneration cycle shall be initiated and observed to confirm correct backwash, brine draw, and air-gap discharge with no overflow or leakage.
+
+## New cation-exchange media shall be disinfected and the system flushed to waste before the treated water is placed in domestic service, in accordance with the manufacturer's start-up procedure.
+
+```datasheet
+label: Commissioning Tests
+type: checkbox
+options:
+ - Incoming vs. treated hardness
+ - Free-chlorine reduction across carbon
+ - Pressure drop per stage at design flow
+ - Observed regeneration cycle and air-gap discharge
+ - Media disinfection and flush-to-waste
+default:
+ - Incoming vs. treated hardness
+ - Pressure drop per stage at design flow
+ - Observed regeneration cycle and air-gap discharge
+ - Media disinfection and flush-to-waste
+```
+
+# Installation {toc}
+
+## Installation places the equipment on the cold-water supply, downstream of backflow protection and upstream of the water heaters, with the bypass, drain, and clearances required for service. {note}
+
+## The treatment equipment shall be installed on the cold-water service downstream of the building backflow protection and upstream of the water heaters and any hydronic heat source.
+
+## Unions or grooved couplings shall be provided at the inlet, outlet, and bypass so that each unit can be removed without cutting piping.
+
+## The equipment shall be set level on a housekeeping pad or manufacturer-approved base, with clearance maintained for media replacement, valve service, and brine-tank refilling.
+
+## The brine and backwash drain shall be installed with the required air gap and pitched to the receiving floor drain.
+
+## Treatment piping requiring insulation shall be insulated in accordance with [[sync/plumbing-insulation]].
+
+## Conditioned-water distribution downstream of the equipment is installed under [[sync/domestic-water-piping]]. {note}
+
+# Delivery, Storage, and Handling {toc}
+
+## Resin, media, and brine salt are sensitive to freezing, moisture, and contamination. {note}
+
+## Resin, media, and brine salt shall be protected from the point of delivery to installation.
+
+## Resin and filter media shall be delivered in the manufacturer's sealed packaging and stored in a clean, dry, conditioned space protected from freezing.
+
+## Equipment shall be stored with all openings capped or plugged to prevent the entry of dirt, debris, and vermin until connection.
+
+## Salt for the brine tank shall be water-softener-grade evaporated or solar salt as recommended by the softener manufacturer and shall be kept dry until use.
+
+# Warranty {toc}
+
+## The treatment-equipment warranty distinguishes the consumable media from the durable control and tank components, which carry different terms. {note}
+
+## The Contractor shall provide the manufacturer's standard warranty for resin and filter media against premature loss of capacity under the specified service conditions.
+
+## The Contractor shall provide the manufacturer's standard warranty for control valves, electronic heads, and pressure vessels.
+
+```datasheet
+label: Warranty Period — Control Valves and Vessels
+type: select
+options:
+ - 1 year
+ - 3 years
+ - 5 years
+ - 10 years
+default: 5 years
+```
+
+# Spare Parts {toc}
+
+## A treatment system consumes filter cartridges, media, and salt, and a defined initial stock keeps the system in service between maintenance visits. {note}
+
+## The Contractor shall furnish one complete set of replacement sediment and carbon cartridges for each housing provided.
+
+## The Contractor shall furnish one initial fill of brine salt sufficient for the first 30 days of operation at the design regeneration frequency.
+
+```datasheet
+label: Spare Parts to Furnish
+type: checkbox
+options:
+ - One spare set of sediment cartridges per housing
+ - One spare set of carbon cartridges per housing
+ - One spare UV lamp and sleeve (if UV provided)
+ - 30-day initial brine salt fill
+default:
+ - One spare set of sediment cartridges per housing
+ - One spare set of carbon cartridges per housing
+ - 30-day initial brine salt fill
+```