NOTE This standard covers private on-site pressurized water distribution piping that conveys potable, reclaimed, or dual-service water across a developed site. (1.1)

NOTE The system begins at the point of connection - the public water main tap, meter vault, or utility owner's facility - and extends through the site distribution network of mains, laterals, and branch services to the building entry point, conventionally taken as 5 feet outside the exterior face of the building. Beyond that line, interior domestic piping governs. (1.2)

NOTE This standard applies where site water distribution is a discrete civil or site-utilities scope rather than a public main installed and accepted by the water utility. (1.3)

NOTE It suits commercial, institutional, industrial, campus, and multi-family residential site development where the distribution network is designed and installed by the project team. It covers distribution loops, dead-end mains with blow-offs, and metered branch services made up with service saddles and corporation stops. (1.4)

NOTE Private fire service mains are outside this standard. (1.8)

NOTE Underground mains that supply fire sprinkler systems, private hydrants, and fire department connections are governed by NFPA 24 and are specified in Underground Fire Service Mains. They carry different testing, restraint, and acceptance requirements and a different Authority Having Jurisdiction; do not combine them into this section. Where a common trench serves both a potable distribution lateral and a fire service lateral, the point of divergence and the inter-utility separation are coordinated at the boundary with that standard. (1.9)

NOTE Interior building domestic water piping is outside this standard. (1.10)

NOTE Piping within 5 feet of the building exterior and all piping inside the building belong to Domestic Water Piping. This standard ends where that one begins. (1.11)

NOTE Site storm drainage is outside this standard. (1.12)

NOTE Inlets, storm sewer, manholes, headwalls, and outfalls are covered by Storm Drainage. (1.13)

NOTE Sanitary sewer collection mains, force mains, and shared dry-utility infrastructure are outside this standard. (1.14)

NOTE Gravity sewer, sewage force mains, dry-utility duct banks, conduit, and manholes that share the site utility corridor are part of Site Utilities, which serves as the omnibus single-section specification when water, sewer, and dry utilities are bid together. Use this standard when water distribution is a standalone scope or a dedicated section is wanted. (1.15)

NOTE Trench excavation, dewatering, shoring, and general structural backfill above the pipe embedment zone are outside this standard. (1.16)

NOTE Those operations are governed by Earthwork, which this standard references but does not duplicate. This standard governs only the bedding and embedment within the pressure-pipe zone. (1.17)

NOTE Backflow prevention assemblies at the service connection are coordinated with Backflow Prevention. (1.18)

NOTE The expanded size range of AWWA C900-22 overlaps the historical range of AWWA C905. (2.3)

NOTE The 2022 revision of AWWA C900 extended its scope to 4 in. through 60 in., which overlaps the 14 in. through 48 in. range historically governed by AWWA C905. For any PVC pipe 14 in. and larger, confirm which document the local utility or Authority Having Jurisdiction requires before submitting, and pin the governing edition in the submittal so dimension ratio and pressure class are unambiguous. Citing both standards without resolving the overlap generates an RFI on every large-diameter PVC submittal. (2.4)

NOTE The Contractor shall employ installers experienced in the installation of pressurized water distribution piping of the type and size specified. (4.1)

NOTE Mechanical joints, restrained joints, and thermoplastic fusion each demand specific technique; improper assembly is the most common cause of test failures and in-service joint separation. Fusion of HDPE in particular shall be performed only by an operator qualified on the equipment in use. (4.2)

NOTE Certification to NSF/ANSI 61 and NSF/ANSI/CAN 372 applies to every wetted component, not pipe alone. (4.5)

NOTE A frequent acceptance delay arises when valves, gaskets, joint lubricants, or coatings lack documented certification even though the pipe is certified. Require the certification mark or listing for each wetted item at submittal so a missing valve listing does not stall acceptance. (4.6)

NOTE The working pressure, surge allowance, depth of cover, and soil conditions establish the pipe class, restraint, and corrosion protection for the system. (5.1)

NOTE Pipe class shall be selected for the maximum sustained working pressure plus a surge allowance, not the static pressure alone. Depth of cover and trench loading enter the ductile iron thickness design per AWWA C150. Soil corrosivity, established by resistivity testing, determines whether polyethylene encasement is required for ductile iron. (5.2)

NOTE Specifying ductile iron in corrosive soil without polyethylene encasement causes early pitting failure. (5.3)

NOTE Where soil resistivity falls below roughly 1500 Ω·cm, or where other corrosion indicators (low pH, chlorides, stray current, cinders, or disturbed fill) are present, bare ductile iron corrodes and can perforate well before its design life. Make the resistivity test and the encasement trigger explicit rather than leaving encasement to field judgment. (5.4)

NOTE Pipe material is selected from ductile iron, PVC, or HDPE based on pressure class, soil corrosivity, installation method, and the local utility's accepted materials. (6.1)

NOTE Ductile iron offers high strength and is widely accepted but is heavier and corrodes in aggressive soil without encasement. PVC is corrosion-resistant and economical for typical distribution pressures. HDPE is fused into a continuous, leak-resistant, restrained string and suits directional drilling and ground likely to move. Confirm the selected material against the serving utility's accepted-materials list before ordering. (6.2)

NOTE Cement-mortar lining prevents tuberculation but is not suited to every water chemistry. (6.4)

NOTE The cement-mortar lining of AWWA C104 protects the pipe bore and preserves carrying capacity in most potable systems. Aggressive or low-alkalinity water can attack the lining, in which case a ceramic-epoxy or polyethylene lining is more durable. Match the lining to the water analysis rather than defaulting in every case. (6.5)

NOTE PVC dimension ratio sets the pressure rating; lower DR means thicker wall and higher rating. (6.7)

NOTE Dimension ratio is the ratio of outside diameter to wall thickness. A lower DR is a thicker wall and a higher pressure rating - DR 18 is rated 235 psi and DR 14 is rated 305 psi for C900 PVC. Select DR for the working pressure plus a surge allowance; rapid valve closure and pump cycling can drive transient pressures well above static. (6.8)

NOTE HDPE forms a continuous restrained string, which changes the restraint and crossing strategy. (6.10)

NOTE Fused HDPE behaves as a continuous, fully restrained pipe with no bell-and-spigot joints to separate, so thrust blocking at in-line fittings is generally unnecessary for the pipe itself. This makes it well suited to horizontal directional drilling and to ground subject to settlement or seismic movement. Mechanical connections to valves and to dissimilar pipe still require restraint and transition fittings. (6.11)

NOTE Joint type is selected by service need: push-on for straight runs, mechanical joint for adjustability, and restrained joint where thrust must be carried by the pipe. (7.1)

NOTE Push-on joints are the economical default for straight runs. Mechanical joints allow field deflection and disassembly. Restrained joints carry thrust through the pipe string and are required at bends, tees, caps, valves, and wherever thrust blocks are impractical or prohibited. (7.2)

NOTE Restraint must extend the full calculated length, not just the fitting. (7.3)

NOTE The restrained joint at a fitting only anchors that fitting; the unbalanced thrust is resisted by the friction and bearing developed over a length of restrained pipe on each side. That length depends on pipe size, design pressure, depth, and soil, and shall be calculated or taken from the utility's standard detail. Restraining only the fitting itself, with unrestrained pipe immediately beyond, leaves the assembly free to pull apart on pressurization. (7.4)

NOTE Every change in direction or termination develops an unbalanced thrust that must be resisted by a thrust block, a restrained-joint system, or a combination. (8.1)

NOTE Internal pressure acting on a bend, tee, cap, or reducer produces a resultant force that will move the fitting and open the joint unless restrained. Concrete thrust blocks transfer this force to undisturbed soil through bearing; restrained-joint systems transfer it into the pipe string. The method is selected per fitting and may combine both. Saturated, loose, or organic soils have low bearing capacity and may rule out thrust blocks entirely. (8.2)

NOTE Undersized thrust blocks fail on first pressurization. (8.3)

NOTE Sizing a block from a generic table without verifying the bearing capacity is a leading cause of joint blowouts. In loose or saturated soil the available bearing can be a fraction of the table assumption, and the block moves under load. Require the designer to confirm the bearing value used, and prefer restrained joints where soil is poor or where blocks would obstruct future excavation. (8.4)

NOTE Isolation valves divide the system into segments that can be shut down for maintenance and repair without taking the whole network out of service. (9.1)

NOTE Valve spacing and the number of services isolated per valve follow the utility master plan and any fire-flow segmentation requirement. Resilient-seated gate valves are the distribution standard; butterfly valves are used on larger transmission mains. Direct-bury valves operate through a valve box; larger or frequently operated valves are set in vaults. (9.2)

NOTE Yard hydrants placed on the distribution main for flushing or utility use shall conform to AWWA C502 and are distinct from private fire hydrants. (9.4)

NOTE Where the site plan locates public-style yard hydrants on the domestic or combination distribution main - for flushing or utility access rather than fire protection - they are dry-barrel hydrants per AWWA C502. Private fire hydrants serving fire protection are part of Underground Fire Service Mains and are not specified here. (9.5)

NOTE The bedding and embedment in the pressure-pipe zone support the pipe, distribute load, and prevent point bearing; the class is matched to the pipe material and native soil. (10.1)

NOTE This standard governs only the zone from the trench bottom to a point above the pipe; general backfill above that zone is governed by Earthwork. Ductile iron is commonly bedded to AWWA C600 Class B - a graded bedding with haunch material worked to the springline. Thermoplastic pipe is bedded and embedded per the embedment classes of AWWA C605, with the class selected for the dimension ratio and native soil. Crushed-stone embedment shall be confined where the native soil could migrate into the voids. (10.2)

NOTE Non-metallic pipe is invisible to electromagnetic locators, so a continuous tracer wire with surface access points is required to find PVC and HDPE mains after backfill. (11.1)

NOTE PVC and HDPE mains cannot be located by induction the way metallic pipe can. A continuous insulated tracer wire taped to the top of the pipe, brought to the surface at regular access points, provides a conductor for electronic locating. Without access points at valve boxes as well as service pits, crews cannot energize and trace the line. (11.2)

NOTE Mandatory separation from sanitary sewer protects the potable main from contamination if either line fails. (12.1)

NOTE Codes require a minimum horizontal and vertical clearance between water mains and sewers, with the water main above the sewer at crossings, so a sewer leak cannot enter the water main. Conflicts found after trenching force costly re-routing, so the separation shall be verified against the civil drawings at design, not in the field. (12.2)

NOTE Pressure and leakage testing confirms the installed system is sound before it is disinfected and placed in service. (13.1)

NOTE Each segment is filled, purged of air, and held at a test pressure above the working pressure for a fixed duration. The allowable leakage is calculated from the segment length, diameter, and test pressure per AWWA C600 for ductile iron or AWWA C605 for thermoplastic; measured make-up water above the allowable indicates a defective joint or fitting. Testing precedes disinfection so leaks are repaired before chlorinated water is introduced. (13.2)

NOTE Disinfection and bacteriological clearance are required before any main is placed in potable service. (14.1)

NOTE A new main is chlorinated to a specified residual, held for a contact time, then flushed and dechlorinated per AWWA C651. The line is not accepted for potable use until two consecutive bacteriological samples, taken at least 24 hours apart, are free of coliform. Specifying "flush until clear" without a minimum flushing velocity and the two-sample requirement creates a dispute over when sampling can begin and routinely delays the schedule. (14.2)

NOTE Pipe, gaskets, and linings degrade if mishandled or left exposed, so protection from delivery through installation is part of the work. (15.1)

NOTE Pipe shall be handled with wide slings, not chains or hooks through the bells, and stored off the ground. PVC and gaskets shall be shaded from prolonged ultraviolet exposure. Open pipe ends shall be plugged whenever work stops so soil, water, and animals do not enter and contaminate the main before disinfection. (15.2)