Water Supply and Distribution

Water Supply and Distribution

Reference text for the water supply area. Every rule below is written from the printed line of the

2024 International Plumbing Code (IPC 2024) that carries it, and each rule names the section it comes

from. Where the printed line does not state a value, no value is stated here.

1. Scope and required water

Chapter 6 governs the materials, design and installation of water supply systems, both hot and cold,

for utilization in connection with human occupancy and habitation, and governs the installation of

individual water supply systems (IPC 2024, 601.1).

Structures equipped with plumbing fixtures and used for human occupancy or habitation must be

provided with a potable supply of water in the amounts and at the pressures specified in the chapter

(IPC 2024, 602.1). Only potable water may be supplied to plumbing fixtures that provide water for

drinking, bathing or culinary purposes, or for the processing of food, medical or pharmaceutical

products; unless the code provides otherwise, potable water must be supplied to all plumbing fixtures

(IPC 2024, 602.2).

Solar energy systems used for heating potable water, or using an independent medium for heating

potable water, must comply with the applicable requirements of the code, and their use must not

compromise the cross-connection or potable-supply protection requirements (IPC 2024, 601.2).

Existing metallic water service piping used for electrical grounding must not be replaced with

nonmetallic pipe or tubing until other approved means of grounding is provided (IPC 2024, 601.3).

The potable water distribution system is tested in accordance with Section 312.6 (IPC 2024, 601.4),

and pressure piping systems rehabilitated with an epoxy lining system must use a lining system

complying with ASTM F2831 (IPC 2024, 601.5).

2. Individual water supply

Where a potable public water supply is not available, individual sources of potable water supply must

be used (IPC 2024, 602.3). The recognized types of individual supply — depending on geological and

soil conditions and the amount of rainfall — are the drilled well, driven well, dug well, bored well,

spring, stream or cistern. Surface bodies of water and land cisterns are not acceptable sources unless

properly treated by approved means to prevent contamination; individual supplies must be constructed

and installed in accordance with applicable state and local laws, and, where those laws do not address

all the requirements of NGWA-01, must comply with NGWA-01 for the requirements those laws do not

address (IPC 2024, 602.3.1).

The combined capacity of source and storage must supply the fixtures with water at the rates and

pressures the chapter requires (IPC 2024, 602.3.2). Water from an individual supply must be approved as

potable by the authority having jurisdiction before connection to the plumbing system (IPC 2024,

602.3.3), and after construction the system must be purged of deleterious matter and disinfected in

accordance with Section 610 (IPC 2024, 602.3.4).

Pumps must be rated for the transport of potable water, be built and installed to prevent

contamination entering the potable supply through the pump units, conform to NSF 61 where they supply

drinking water, be sealed to the well casing or covered with a watertight seal, be designed to

maintain a prime, and be installed with ready access to the pump parts of the entire assembly for

repairs (IPC 2024, 602.3.5). The pump room or enclosure around a well pump must be drained and

protected from freezing by heating or other approved means; pumps installed in basements must be

mounted on a block or shelf not less than 18 inches (457 mm) above the basement floor, and well pits

are prohibited (IPC 2024, 602.3.5.1).

3. Water service

The water service pipe must be sized to supply the structure in the quantities and at the pressures

the code requires, and must be not less than 3/4 inch (19.1 mm) in diameter (IPC 2024, 603.1).

Separation from the building sewer, where the water service is in the same trench: if the building

sewer is not constructed of a material listed in Table 702.2, water service pipe and building sewer

must be horizontally separated by not less than 5 feet (1524 mm) of undisturbed or compacted earth.

That separation does not apply where the water service crosses a sewer pipe, provided the water

service is sleeved to a point not less than 5 feet (1524 mm) horizontally from the sewer pipe

centerline on both sides of the crossing; the sleeve must be of pipe materials listed in Table 605.3,

702.2 or 702.3. It also does not apply where the bottom of the water service pipe, within 5 feet

(1524 mm) of the sewer, is not less than 12 inches (305 mm) above the highest point of the top of the

building sewer (IPC 2024, 603.2). Potable water service pipes must not be located in, under or above

cesspools, septic tanks, septic tank drainage fields or seepage pits; where soil or ground water

creates contaminated conditions for piping, analysis is required in accordance with Section 605.1

(IPC 2024, 603.2.1).

Pipe selection. Water service pipe must conform to NSF 61 and to one of the standards listed in

Table 605.3. Water service pipe or tubing installed underground and outside the structure must have a

working pressure rating of not less than 160 psi (1100 kPa) at 73.4°F (23°C); where the water pressure

exceeds 160 psi (1100 kPa), the piping material must have a working pressure rating not less than the

highest available pressure. Water service piping materials that are not third-party certified for

water distribution must terminate at or before the full-open valve located at the entrance to the

structure, and ductile iron water service piping must be cement mortar lined in accordance with

AWWA C104/A21.4 (IPC 2024, 605.3). Dual check-valve-type backflow preventers installed on the water

supply system must comply with ASSE 1024 or CSA B64.6 (IPC 2024, 605.3.1).

Water distribution pipe and tubing must conform to NSF 61 and to one of the standards listed in

Table 605.4, and hot water distribution pipe and tubing must have a pressure rating of not less than

100 psi (690 kPa) at 180°F (82°C) (IPC 2024, 605.4).

Water distribution is served by a shorter list: CPVC, CPVC/AL/CPVC, copper or copper-alloy pipe and

tubing, PEX, PEX-AL-PEX, PEX-AL-HDPE, ductile iron, galvanized steel, PE-AL-PE composite, PE-RT,

polypropylene, and stainless steel pipe and tubing of Type 304/304L and 316/316L (IPC 2024,

Table 605.4).

4. Design of the building water distribution system

The design must conform to accepted engineering practice, and the methods used to determine pipe sizes

must be approved (IPC 2024, 604.1). At the points of interconnection between the hot and cold water

supply piping systems and the individual fixtures, appliances or devices, provisions must be made to

prevent flow between those piping systems (IPC 2024, 604.2).

4.1 Required capacity at fixture supply outlets (Table 604.3)

Under conditions of peak demand, the capacities at the fixture supply pipe outlets must be not less

than the values of Table 604.3; for fixtures and appliances not listed there, the minimum flow rate

and flow pressure follow the manufacturer's installation instructions (IPC 2024, 604.3).

For SI: 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 3.785 L/m. Where the shower mixing

valve manufacturer indicates a lower flow rating for the mixing valve, the lower value applies

(IPC 2024, Table 604.3, footnote b).

4.2 Maximum flow and water consumption (Table 604.4)

Maximum water consumption flow rates and quantities for all plumbing fixtures and fixture fittings

follow Table 604.4 (IPC 2024, 604.4).

A hand-held shower spray is a shower head, and shower heads must comply with all requirements for

high-efficiency showerheads in ASME A112.18.1-2020/CSA B125.1 (IPC 2024, Table 604.4, footnotes a

and c). The exceptions to Section 604.4 are blowout design water closets having a water consumption

not greater than 3 1/2 gallons (13 L) per flushing cycle, vegetable sprays, clinical sinks having a

water consumption not greater than 4 1/2 gallons (17 L) per flushing cycle, service sinks and

emergency showers.

4.3 Size of fixture supply (Table 604.5)

The minimum size of a fixture supply pipe follows Table 604.5. The fixture supply pipe must terminate

not more than 30 inches (762 mm) from the point of connection to the fixture; a reduced-size flexible

water connector installed between the supply pipe and the fixture must be of an approved type, and the

supply pipe must extend to the floor or wall adjacent to the fixture. The minimum size of individual

distribution lines used in gridded or parallel water distribution systems also follows Table 604.5

(IPC 2024, 604.5).

Where the developed length of the distribution line is 50 feet or less and the available pressure at

the meter is 35 psi or greater, the minimum size of an individual distribution line supplied from a

manifold and installed as part of a parallel water distribution system may be one nominal tube size

smaller than the sizes indicated (IPC 2024, Table 604.5, footnote a).

4.4 Pressure, flow control and manifolds

Where street water main pressures fluctuate, the building water distribution system must be designed

for the minimum pressure available (IPC 2024, 604.6). Wherever the pressure from the street main or

other source is insufficient to provide the flow pressures at fixture outlets required by Table 604.3,

a water pressure booster system conforming to Section 606.5 must be installed on the building water

supply system (IPC 2024, 604.7).

Where water pressure within a building exceeds 80 psi (552 kPa) static, an approved water

pressure-reducing valve conforming to ASSE 1003 or CSA B356 with strainer must be installed to reduce

the pressure in the building water distribution piping to not greater than 80 psi (552 kPa) static.

The exception covers service lines to sill cocks and outside hydrants, and main supply risers where

pressure from the mains is reduced to 80 psi (552 kPa) or less at individual fixtures (IPC 2024,

604.8). The valve must be designed to remain open to permit uninterrupted water flow in case of valve

failure (IPC 2024, 604.8.1), and valves, regulators and strainers must be constructed and installed so

that parts can be repaired or removed without breaking a pipeline or removing the valve and strainer

from the pipeline (IPC 2024, 604.8.2).

The flow velocity of the distribution system must be controlled to reduce the possibility of water

hammer; a water-hammer arrestor must be installed where quick-closing valves are used, installed in

accordance with the manufacturer's instructions, and must conform to ASSE 1010 (IPC 2024, 604.9).

Hot and cold water manifolds installed with gridded or parallel connected individual distribution

lines to each fixture or fixture fitting must be sized in accordance with Table 604.10.1, where the

total gallons per minute is the demand of all outlets supplied (IPC 2024, 604.10.1).

Individual fixture shutoff valves installed at the manifold must be identified as to the fixture

being supplied (IPC 2024, 604.10.2), and access must be provided to manifolds with integral factory-

or field-installed valves (IPC 2024, 604.10.3). Individual pressure balancing in-line valves for

individual fixture fittings must comply with ASSE 1066, must be installed in a location with access,

and must not be used alone as a substitute for the balanced pressure, thermostatic or combination

shower valves required in Section 412.3 (IPC 2024, 604.11).

5. Materials, joints and valves

Installation of a water service or water distribution pipe is prohibited in soil and ground water

contaminated with solvents, fuels, organic compounds or other detrimental materials causing

permeation, corrosion, degradation or structural failure of the piping material; where detrimental

conditions are suspected, a chemical analysis of the soil and ground water is required, and where

detrimental conditions exist, approved alternative materials or routing are required (IPC 2024,

605.1).

Pipe and pipe fittings, including valves and faucets, used in the water supply system must have not

more than 8 percent lead content (IPC 2024, 605.2). Pipe, fittings, joints, valves, faucets and

fixture fittings used to supply water for drinking or cooking purposes must comply with NSF 372 and

must have a weighted average lead content of 0.25 percent or less (IPC 2024, 605.2.1).

Fittings must be approved for installation with the piping material installed and comply with the

applicable standards listed in Table 605.5; fittings used in water supply systems must also comply

with NSF 61, and ductile and gray iron pipe and fittings used in water service piping systems must be

cement mortar lined in accordance with AWWA C104/A21.4 (IPC 2024, 605.5). Flexible water connectors

exposed to continuous pressure must conform to ASME A112.18.6/CSA B125.6, and access must be provided

to all flexible water connectors (IPC 2024, 605.6). Valves must be compatible with the type of piping

material installed in the system, conform to one of the standards listed in Table 605.7 or be

approved, and, where intended to supply drinking water, meet NSF 61 (IPC 2024, 605.7). Manufactured

pipe nipples must conform to one of the standards listed in Table 605.8 (copper, copper alloy and

chromium-plated: ASTM B687; steel: ASTM A733) (IPC 2024, 605.8).

Prohibited joints and connections in the water supply system are: cement or concrete joints; joints

made with fittings not approved for the specific installation; solvent-cement joints between

different types of plastic pipe; and saddle-type fittings (IPC 2024, 605.9).

6. Installation: valves, boosters, tanks and testing

Full-open valves must be installed in these locations (IPC 2024, 606.1):

buildings three stories or less in height where a common water supply piping system supplies other

than one- and two-family dwellings, a main shutoff valve must be provided for each tenant.

occupancies that are two stories or less in height and in one- and two-family residential

occupancies.

occupancies.

fixture equipped with individual stops.

Shutoff valves must be installed on the fixture supply to each plumbing fixture other than bathtubs

and showers in one- and two-family residential occupancies and other than in individual dwelling or

sleeping units that are provided with unit shutoff valves in hotels, motels, boarding houses and

similar occupancies; on the water supply pipe to each sill cock; and on the water supply pipe to each

appliance or mechanical equipment (IPC 2024, 606.2). Access must be provided to all full-open valves

and shutoff valves (IPC 2024, 606.3). Service and hose bibb valves must be identified, and other

valves installed in locations that are not adjacent to the fixture or appliance must be identified

as to the fixture or appliance served (IPC 2024, 606.4).

Where the water pressure in the public water main or individual water supply system is insufficient

to supply the minimum pressures and quantities specified in the code, the supply must be supplemented

by an elevated water tank, a hydropneumatic pressure booster system or a water pressure booster pump

installed in accordance with Section 606.5.5 (IPC 2024, 606.5.1). Within a booster system: a

low-pressure cutoff must be installed on all booster pumps to prevent creation of a vacuum or negative

pressure on the suction side of the pump when a positive pressure of 10 psi (68.94 kPa) or less occurs

on the suction side (IPC 2024, 606.5.5); potable water inlets to gravity tanks must be controlled by a

fill valve or other automatic supply valve installed so as to prevent the tank from overflowing, with

the inlet terminated to provide an air gap not less than 4 inches (102 mm) above the overflow

(IPC 2024, 606.5.6); and every pressure tank in a hydropneumatic pressure booster system must be

protected with a pressure relief valve set at a maximum pressure equal to the rating of the tank,

installed on the supply pipe to the tank or on the tank, discharging by gravity to a safe place of

disposal (IPC 2024, 606.5.10).

Water supply tanks must be covered to keep out unauthorized persons, dirt and vermin; the covers of

gravity tanks must be vented with a return bend vent pipe with an area not less than the area of the

down-feed riser pipe, screened with a corrosion-resistant screen of not less than 16 by 20 mesh per

inch (IPC 2024, 606.5.3). A gravity or suction water supply tank must have an overflow sized by

Table 606.5.4, discharging not less than 6 inches (152 mm) above the roof or roof drain, floor or

floor drain, or over an open water-supplied fixture, and covered with a corrosion-resistant screen of

not less than 16 by 20 mesh per inch and by 1/4-inch (6.4 mm) hardware cloth or terminating in a

horizontal angle seat check valve (IPC 2024, 606.5.4).

A drain pipe with a valve must be provided at the lowest point of each tank to permit emptying, must

discharge as required for overflow pipes, and must be not smaller than Table 606.5.7 (IPC 2024,

606.5.7).

Potable water gravity tanks or manholes of potable water pressure tanks must not be located directly

under any soil or waste piping or any source of contamination (IPC 2024, 606.5.8). Water pressure

tanks must be provided with a vacuum relief valve at the top of the tank operating up to a maximum

water pressure of 200 psi (1380 kPa) and up to a maximum temperature of 200°F (93°C), not less than

1/2 inch (12.7 mm) in size; the section does not apply to pressurized captive air

diaphragm/bladder tanks (IPC 2024, 606.5.9).

Testing: upon completion of a section of or the entire water supply system, the system or portion

completed must be tested in accordance with Section 312 (IPC 2024, 606.6). Section 312.6 requires the

system to be tested and proved tight under a water pressure not less than the working pressure of the

system, or — for piping systems other than plastic — by an air test of not less than 50 psi

(344 kPa), with the pressure held for not less than 15 minutes, and the water used for tests obtained

from a potable source (IPC 2024, 312.6).

7. Hot water supply system

In residential occupancies, hot water must be supplied to plumbing fixtures and equipment used for

bathing, washing, culinary purposes, cleansing, laundry or building maintenance; in nonresidential

occupancies, hot water must be supplied for culinary, cleansing, laundry or building maintenance

purposes, and hot water or tempered water must be supplied for bathing and washing purposes

(IPC 2024, 607.1). A thermostat control for a water heater serves as the temperature limiting means

only where the water heater complies with ASSE 1082 or ASSE 1085 (IPC 2024, 607.1.1). Tempered water

must be controlled by a limiting device conforming to ASSE 1070/ASME A112.1070/CSA B125.70 and set to

not greater than 110°F (43°C), by a thermostatic mixing valve conforming to ASSE 1017, by a water

heater conforming to ASSE 1082, or by a water heater conforming to ASSE 1084; this does not supersede

the requirement for protective shower valves in accordance with Section 412.3 (IPC 2024, 607.1.2).

The developed length of hot or tempered water piping, from the source of hot water to the fixtures

that require hot or tempered water, must not exceed 50 feet (15 240 mm); recirculating system piping

and heat-traced piping are considered sources of hot or tempered water (IPC 2024, 607.2). Where a

storage water heater is supplied with cold water that passes through a check valve, pressure reducing

valve or backflow preventer, a thermal expansion control device must be connected to the water heater

cold water supply pipe at a point downstream of all check valves, pressure reducing valves and

backflow preventers; thermal expansion tanks must be sized per the tank manufacturer's instructions

and such that the pressure in the water distribution system does not exceed that required by

Section 604.8 (IPC 2024, 607.3). Fixture fittings, faucets and diverters must be installed and adjusted

so that the flow of hot water from the fittings corresponds to the left-hand side of the fixture

fitting, with an exception for shower and tub/shower mixing valves conforming to

ASSE 1016/ASME A112.1016/CSA B125.16 or ASME A112.18.1/CSA B125.1 where the flow of hot water

corresponds to the markings on the device (IPC 2024, 607.4).

8. Protection of the potable water supply

A potable water supply system must be designed, installed and maintained so as to prevent

contamination from nonpotable liquids, solids or gases being introduced into the potable water supply

through cross connections or any other piping connections to the system; backflow preventer

applications must conform to Table 608.1, except as specifically stated in Sections 608.2 through

608.17.10 (IPC 2024, 608.1).

Table 608.1 (application of backflow preventers) — selected devices, degree of hazard, application and

standard:

In Table 608.1, "low hazard" is pollution and "high hazard" is contamination, both as defined in

Section 202 (IPC 2024, Table 608.1, footnotes a and b).

8.1 Means of protection

The minimum required air gap is measured vertically from the lowest end of a potable water outlet to

the flood level rim of the fixture or receptacle into which the outlet discharges; air gaps must

comply with ASME A112.1.2 and air gap fittings with ASME A112.1.3, and products listed and labeled to

those standards are considered in compliance (IPC 2024, 608.14.1).

Reduced pressure principle backflow prevention assemblies must conform to ASSE 1013, AWWA C511,

CSA B64.4 or CSA B64.4.1, and reduced pressure detector assembly backflow preventers to ASSE 1047;

they may be installed where subject to continuous pressure, and the relief opening must discharge by

air gap and be prevented from being submerged (IPC 2024, 608.14.2). Backflow preventers with

intermediate atmospheric vents must conform to ASSE 1012, ASSE 1081 or CSA B64.3, may be installed

under continuous pressure, and their relief opening must discharge by air gap and be prevented from

being submerged (IPC 2024, 608.14.3). Barometric loops must precede the point of connection and extend

vertically to a height of 35 feet (10 668 mm), and may be used only as an atmospheric-type or

pressure-type vacuum breaker (IPC 2024, 608.14.4). Pressure vacuum breaker assemblies must comply with

ASSE 1020 or CSA B64.1.2, spill-resistant vacuum breaker assemblies with ASSE 1056 or CSA B64.1.3, and

these assemblies must be installed with the critical level located not less than 12 inches (305 mm)

above all downstream piping and outlets; pressure vacuum breaker assemblies must not be installed

where spillage could cause damage to the structure (IPC 2024, 608.14.5). Double check backflow

prevention assemblies must conform to ASSE 1015, CSA B64.5, CSA B64.5.1 or AWWA C510, double check

detector fire protection assemblies to ASSE 1048, and these assemblies must be capable of operating

under continuous pressure conditions (IPC 2024, 608.14.7). Dual check backflow preventers must comply

with ASSE 1024 or CSA B64.6 (IPC 2024, 608.14.9), and backflow devices for chemical dispensers must

comply with ASSE 1055 or be equipped with an air gap fitting (IPC 2024, 608.14.8).

Access must be provided to backflow preventers as specified by the manufacturer's instructions

(IPC 2024, 608.15). They must not be located in areas subject to freezing except where they can be

removed by means of unions or are protected from freezing by heat, insulation or both (IPC 2024,

608.15.2), and the termination of piping from the relief port or air gap fitting must discharge to an

approved indirect waste receptor or to the outdoors where it will not cause damage or create a

nuisance, with the receptor and drainage piping sized to drain the maximum discharge flow rate from

the relief port as published by the manufacturer (IPC 2024, 608.15.2.1).

8.2 Protection of potable water outlets

Openings and outlets must be protected by an air gap between the opening and the fixture flood level

rim as specified in Table 608.16.1; openings and outlets equipped for hose connection must be

protected by means other than an air gap (IPC 2024, 608.16.1).

The "away from a wall" column applies where walls or obstructions are spaced from the nearest

inside-edge of the spout opening a distance greater than three times the diameter of the effective

opening for a single wall, or greater than four times the diameter of the effective opening for two

intersecting walls (IPC 2024, Table 608.16.1, footnote a).

Where openings and outlets are protected by vacuum breakers, the critical level of the vacuum breaker

must be set not less than 6 inches (152 mm) above the flood level rim of the fixture or device; fill

valves must be set in accordance with Section 415.3.1; vacuum breakers must not be installed under

exhaust hoods or similar locations that will contain toxic fumes or vapors; and pipe-applied vacuum

breakers must be installed not less than 6 inches (152 mm) above the flood level rim of the fixture,

receptor or device served (IPC 2024, 608.16.4). Approved deck-mounted or equipment-mounted vacuum

breakers, and faucets with integral atmospheric vacuum breakers or spill-resistant vacuum breaker

assemblies, must be installed in accordance with the manufacturer's instructions and the requirements

for labeling, with the critical level not less than 1 inch (25 mm) above the flood level rim

(IPC 2024, 608.16.4.1). Sill cocks, hose bibbs, wall hydrants and other openings with a hose

connection must be protected by an atmospheric-type or pressure-type vacuum breaker or a permanently

attached hose connection vacuum breaker, except for water heater and boiler drain valves with hose

connection threads intended only for tank or vessel draining, and water supply valves intended for

connection of clothes washing machines where backflow prevention is otherwise provided or integral

with the machine (IPC 2024, 608.16.4.2).

8.3 Health care plumbing (highlights)

Health care plumbing systems must conform to Section 609 in addition to the other requirements of the

code, and the provisions apply to Group I-1, Group I-2, ambulatory care facilities, medical offices,

research and testing laboratories, and Group F facilities manufacturing pharmaceutical drugs and

medicines (IPC 2024, 609.1). Group I-2, Condition 2 facilities must have not fewer than two water

service pipes sized so that, with the loss of the largest service pipe, the remaining service pipes

meet the water demand for the entire facility, each service with a shutoff valve in the building and a

shutoff valve at the utility-provided point of connection (IPC 2024, 609.2). Vacuum breakers in health

care plumbing must be installed not less than 6 inches (152 mm) above the flood level rim of the

fixture or device in accordance with Section 608, and the flood level rim of hose connections is the

maximum height at which any hose is utilized (IPC 2024, 609.4).

9. Disinfection and treatment

New potable water systems must be purged of deleterious matter and disinfected prior to utilization.

The method is that prescribed by the health authority or water purveyor having jurisdiction or, in the

absence of a prescribed method, the procedure described in AWWA C651 or AWWA C652 or in Section 610;

the requirement applies to on-site or in-plant fabrication of a system or of a modular portion of a

system (IPC 2024, 610.1). The procedure published in the section is: flush the pipe system with clean,

potable water until dirty water does not appear at the points of outlet; fill the system or part with

a water/chlorine solution containing not less than 50 parts per million (50 mg/L) of chlorine, valve

it off and let it stand for 24 hours, or fill with a solution containing not less than 200 parts per

million (200 mg/L) of chlorine and let it stand for 3 hours; then flush with clean potable water until

the chlorine is purged; and repeat the procedure where a bacteriological examination shows

contamination remains (IPC 2024, 610.1, items 1 through 4).

Point-of-use reverse osmosis drinking water treatment units must comply with CSA B483.1 or NSF 58, and

drinking water treatment units must meet CSA B483.1, NSF 42, NSF 44, NSF 53 or NSF 62 (IPC 2024,

611.1). The discharge from a reverse osmosis drinking water treatment unit must enter the drainage

system through an air gap or an air gap device meeting CSA B483.1 or NSF 58 (IPC 2024, 611.2), and

tubing to and from drinking water treatment units must be of a size and material recommended by the

manufacturer and comply with NSF 14, NSF 42, NSF 44, NSF 53, NSF 58 or NSF 61 (IPC 2024, 611.3).

Solar systems for domestic hot water heating and similar uses must be constructed and installed in

accordance with the International Mechanical Code (IPC 2024, 612.1). Temperature-actuated mixing

valves installed to reduce water temperatures to defined limits must comply with ASSE 1017 and be

installed at the hot water source (IPC 2024, 613.1).