A. 
Buildings. Every building equipped with plumbing fixtures and used for human occupancy or habitation shall be provided with a potable supply of cold water in the amounts and at the pressures specified in this chapter. For permanent residences or buildings in which people are employed, hot water shall be provided. The hot water supply to any fixture requiring hot water shall be installed on the left side of the fixture.
B. 
Use of non-potable water prohibited. Only potable water shall be accessible to plumbing fixtures supplying water for drinking, bathing, culinary use or the processing of food, medical or pharmaceutical products.
A. 
Size of water service. The water service pipe shall be of sufficient size to furnish water to the building in the quantities and at the pressures required elsewhere in this code. It shall in no case, be less than 3/4 inch nominal diameter. Methods for sizing the water service pipe are described in Article XVI.
(1) 
Protection of water service. Newly installed or replaced water service piping shall be provided with a backflow device located at or near the water meter. Dual check valves, double check valves, and reduced pressure zone type backflow preventers are acceptable for the purpose of this section.
B. 
Separation of water service and building sewer.
(1) 
Except as permitted below, the underground water service pipe and the building drain or building sewer shall be not less than 10 feet apart horizontally and shall be separated by undisturbed or compacted earth.
(2) 
The water service pipe may be placed in the same trench with the building drain and building sewer provided approval is given by the Administrative Authority and the following conditions are met:
(a) 
The bottom of the water service pipe, at all points, shall be at least 12 inches above the top of the sewer line at its highest point.
(b) 
The water service pipe shall be placed on a solid shelf excavated at one side of the common trench.
(c) 
The number of joints in the service pipe shall be kept to a minimum.
(d) 
The sewer material shall be of an approved type.
(e) 
Where the location of plumbing fixtures in the building make it impracticable due to lot condition and/or topography either to maintain a horizontal separation of 10 feet between water service lines and building drain or sewer lines, or a vertical separation of one foot with the water service pipe above the building drain or sewer, the water service pipe shall be enclosed in a continuous, impervious plastic sheath with ends properly sealed below grade from where required separations are not met to a point not less than six inches above the top of the finished concrete floor, minimum water line and sewer line depths required by this code shall be adhered to at all times. The Administrative Authority shall notify the homeowner of the existence of any plastic sheathing used outside the building foundation. This notification shall be included in the final inspection certificate.
C. 
Water service near sources of pollution. Potable water service pipes shall not be located in, under or above cesspools, septic tanks, septic tank drainage fields or seepage pits. A separation of 10 feet shall be maintained. Where the water service must cross the sewer line, the bottom of the water service within 10 feet of the point of crossing, shall be at least 12 inches above the top of the sewer line. The sewer line shall be of approved material at least 10 feet on either side of the crossing.
D. 
Water service pipe through wall. Clearance shall be provided around a water service pipe passing through walls to protect against (a) chemical action from direct contact with concrete, (b) distortion or rupture of water service pipe from shearing action due to settlement, (c) distortion or rupture of the water service pipe caused by expansion or contraction. Sleeves or wall seal shall be a minimum of one pipe size larger than the pipe passing through or arches may be used to provide the wall opening. The space between the pipe and wall structure shall be carefully packed or caulked with lead or waterproof and rodent resistant material.
The design of the building hot and cold water distribution system shall conform to good engineering practice. Methods used to determine pipe sizes shall be acceptable to the Administrative Authority. (A guide to the design of building water supply systems is given in Article XVI.)
A. 
Size of fixture supply. The minimum sizes of a fixture supply pipe shall be shown in Table 860-177A, "Minimum sizes of Fixture Water Supply Pipes." The fixture supply pipe shall be extended to within at least 30 inches of the point of connection to the fixture.
Table 860-177A
Minimum Sizes of Fixture Water Supply Lines
Type of Fixture or Devices
Nominal Pipe Size
(inches)
Bathtubs
1/2
Combination sink and tray
1/2
Drinking fountain
3/8
Dishwasher (domestic)
1/2
Kitchen sink (residential)
1/2
Kitchen sink (commercial)
1/2
Lavatory
3/8
Laundry tray, 1, 2, or 3 comp.
1/2
Shower (single head)
1/2
Sinks (service, slop)
1/2
Sinks, flushing rim
3/4
Urinal (flush tank)
1/2
Urinal (direct flush valve)
3/4
Water closet (tank type)
3/8
Water closet (flush valve type)
1
Hose bibbs
1/2
Wall hydrant
1/2
B. 
High street main pressures. Where the service water pressure to a building exceeds 80 psi, an approved water pressure regulator with strainer shall be installed to reduce the pressure to the building. Sill cocks and outside hydrants and fire line supply may be left on full main pressure at the option of the owner. The pressure reducing valve shall be set to reduce the water pressure to 80 psi or lower, depending on the building requirements. A gauge shall be installed on the house side of said pressure regulator in an accessible location for inspection and repair.
C. 
Water hammer. All building water supply systems in which quick acting valves are installed shall be provided with devices to absorb high pressures resulting from the quick closing of these valves. Mechanical Devices: Where mechanical devices are used the manufacturer's specifications shall be followed as to location and method of installation.
D. 
Inadequate water pressure. Whenever water pressure from the street main or other source of supply is insufficient to provide flow pressures at fixture outlets as required under Subsection G, a booster pump and pressure tank or other approved means shall be installed on the building water supply system.
E. 
Variable street pressures. Where street water main pressures fluctuate, the building water distribution system shall be designed for the minimum pressure available.
F. 
Supply demand. The supply demand in gallons per minute in the building water distributing system shall be determined on the basis of the load in terms of supply fixture units and of the relationship between load and supply demand. (See Article XVI, § 860-183, for suggested procedure).
G. 
Minimum pressures required in water distribution system. Based on the minimum static water pressure available, pipe sizes shall be selected so that under conditions of peak demand a minimum flow pressure at the point of discharge shall not be less than shown in Table 860-177G, "Minimum Flow Pressure and Flow Rates."
Table 860-177G
Minimum Flow Pressure and Flow Rates
Location
Flow Pressure
(psi)
Rate
(gpm)
Ordinary basin faucet
8
2.0
Self-closing basin faucet
8
2.5
Sink faucet, 3/8 inch
8
4.5
Sink faucet, 1/2 inch
8
4.5
Bathtub faucet
8
6.0
Laundry tub cock, 1/2 inch
8
5.0
Shower
8
5.0
Ball-cock for closet
8
3.0
Flush valve for closet
15
15.35
Flushometer valve for urinal
15
*15.0
Drinking fountains
15
0.75
Sill cock-Wall hydrant
10
5.0
NOTE:
*
Wide range due to variation in design and type of flush valves.
A. 
Water supply control valves.
(1) 
Stop and waste valves prohibited. Combination stop-and-waste valves or cocks shall not be installed underground in water service piping.
(2) 
Curb valve. On each water service from a street main to a building an approved gate valve or ground key stopcock shall be installed near the curbline between the property line and the curb. This valve or stopcock shall be provided with an approved curb valve box and shall not be under a driveway.
(3) 
Building valve. Each building water service shall be provided with a shut-off valve located inside the building near the point the water service enters.
(4) 
Meter valve. Where a shut-off valve is installed in the line on the discharge side of a water meter, the valve shall not be less than the building water service.
(5) 
Riser valves. Except in single family dwellings a valve shall be installed at the foot of each water supply riser. In multi-story buildings a valve shall be installed at the top of each water supply downfeed pipe from a booster system.
(6) 
Valves in dwelling units. In two-family or multiple family dwelling units one or more control valves shall be provided so that the water to any unit may be shut off without stopping flow of water to other units. These valves shall be readily accessible inside the unit controlled.
(7) 
Individual fixture valves. In all building classifications, the water service line to each fixture or other piece of equipment shall be provided with a valve or fixture stop to shut off the water to the fixture. All sill cocks and wall hydrants shall be separately controlled by a valve inside the building.
(8) 
Tank controls. Supply lines from pressure or gravity tanks shall be valved at or near the tanks.
(9) 
Water heating equipment valve. The cold water branch to each hot water storage tank or water heater shall be provided with a valve located near the equipment. Each tank or heater shall be equipped with an approved automatic relief valve as specified in § 860-180B.
(10) 
Valves to be accessible. All water supply control valves shall be placed as to be accessible for service and maintenance. All concealed tub or shower valves shall be provided with renewable seats.
(11) 
Control valve design. Except to single fixtures, control valves on all water lines shall when fully opened, have a cross sectional area not less than 85% of the cross sectional area of the line in which they are installed.
B. 
Water pressure booster systems.
(1) 
Water pressure booster system required. When the water pressure in the public water main or individual water supply system is insufficient to supply the probably peak demand flow to all plumbing fixtures and other water needs freely and continuously with the minimum pressures and quantities specified in § 860-177G or elsewhere in this code and in accordance with good practice, the rate of supply shall be supplemented by:
(a) 
An elevated water tank.
(b) 
A hydro-pneumatic pressure booster system.
(c) 
A water pressure booster pump installed in accordance with Subsection B(5).
(2) 
Support. All water supply tanks shall be supported in accordance with the building code or other regulations which apply.
(3) 
Covers. All water supply tanks shall be covered to keep out unauthorized persons, dirt and vermin. The covers of gravity tanks shall be vented with a return bend vent pipe having an area not less than the area of the down feed riser pipe and the vent shall be screened with corrosion resistant screen of not less than 16 by 20 mesh.
(4) 
Overflows for water supply tanks. Each gravity or suction water supply tank shall be provided with an overflow having a diameter not less than show in Table 860-178B(4), "Sizes of Overflow Pipes for Water Supply Tanks." The overflow outlet shall discharge above and within not less than six inches of a roof or roof drain, floor or floor drain, or over an open water supplied fixture. The overflow outlet shall be covered by a corrosion resistant screen of not less than 16 by 20 mesh to the inch and by 1/4 inch hardware cloth or shall terminate in a horizontal angle seat check valve. Drainage from overflow pipes shall be directed so as not to freeze on roof walkways.
Table 860-178B(4)
Sizes of Overflow Pipes for Water Supply Tanks
Maximum Capacity of Water Supply Line to Tank
(gpm)
Diameter of Overflow Pipe
(inches ID)
0 — 50
2
50 — 150
2 1/2
100 — 200
3
200 — 400
4
400 — 700
5
700 — 1,000
6
Over 1,000
8
(5) 
Low pressure cut-off required on booster pumps. When a booster pump is used on a water pressure booster system and the possibility exists that a positive pressure of 10 psi or less may occur on the suction side of the pump, there shall be installed a low pressure cut-off on the booster pump to prevent the creation of a vacuum or negative pressure on the suction side of the pump, thus cutting off water to other outlets.
(6) 
Potable water inlet control and location. Potable water inlet to gravity tanks shall be controlled by a ballcock or other automatic supply valve so installed as to prevent the tank from overflowing. The inlet shall be terminated so as to provide an accepted air gap but in no case less than four inches above the overflow.
(7) 
Tank drain pipes. Each tank shall be provided at its lowest point with a valved pipe to permit emptying the tank which shall discharge as required for overflow pipes and not smaller in size than shown in Table 860-178B(7), "Size of Drain Pipes for Water Tanks."
Table 860-178B(7)
Size of Drain Pipes for Water Tanks
Tank Capacity
(gallons)
Drain Pipe
(inches)
Up to 750
1
751 to 1,500
1 1/2
1,501 to 3,000
2
3,001 to 5,000
2 1/2
5,001 to 7,500
3
Over 7,500
4
(8) 
Prohibited location of potable supply tanks. Potable water gravity tanks or manholes of potable water pressure tanks shall not be located directly under any soil or waste piping.
(9) 
Pressure tanks — vacuum relief. All potable water pressure tanks shall be provided with a vacuum relief valve at the top of the tank which will operate up to a maximum water pressure of 200 psi and to maximum water temperatures of 200° F. The minimum size of each vacuum relief valve shall be 1/2 inch.
(10) 
Pumps and other appliances. Waterpumps, filters, softeners, tanks and all other appliances and devices used to handle or treat potable water shall be protected against contamination.
A. 
General. A potable water supply system shall be designed, installed and maintained in such manner as to prevent contamination from non-potable liquids, solids, or gases from being introduced into the water supply through cross connections or piping connections to the system.
B. 
Identification of potable and nonpotable water. In all buildings where dual water distribution systems, one potable water and the other nonpotable water, are installed, each system shall be identified either by color marking or metal tags.
(1) 
Color marking. When color marking is used, potable water lines shall be painted green and nonpotable water lines shall be painted yellow. This requirement may be met by painting three inch wide bands green or yellow at intervals of not more than 25 feet and at points where piping passes through walls, floors or roofs in which case the bands shall be applied to the piping on both sides of the walls and both above and below the floor or roof. Points of outlets for nonpotable water shall be marked with a tag or color coded.
(2) 
Metal tags.
(a) 
When tags are used, potable water lines shall be identified by 3-inch diameter metal tags bearing the legend Safe Water in letters not less than one-half inch in height. This requirement is not meant to limit or restrict the use of identification tags used for other identifying purposes.
(b) 
Nonpotable water lines shall be identified by firmly attached, metal tags having the shape of a four inch equilateral triangle bearing the legend Water Unsafe in letters not less than 7/16 inch in height.
(c) 
As in the use of color bands, tags shall be attached to pipes at intervals of not more than 25 feet and at either side of points where pipes pass through walls and above and below points where pipes pass through floors or roofs.
C. 
Cross connection control. Cross connections between potable water systems and other systems or equipment containing water or other substances of unknown or questionable safety are prohibited except when and where, as approved by the authority having jurisdiction, suitable protective devices such as the reduced pressure zone backflow preventer or equal are installed, tested, and maintained to insure proper operation on a continuing basis.
(1) 
Individual water supplies. Cross connections between an individual water supply and a potable public supply shall not be made unless specifically approved by the authority having jurisdiction.
D. 
Interconnections. Public water supplies. Interconnection between two or more public water supplies shall be permitted only with the approval of the health authority having jurisdiction.
E. 
Toxic materials.
(1) 
Construction. Piping conveying potable water shall be constructed of nontoxic material.
(2) 
Materials and substances. No materials or substances that could produce either toxic conditions, taste, order or discoloration in a potable water system shall be introduced into or used in such systems.
(3) 
Painting of water tanks. The interior surface of a potable water tank shall not be lined, painted, or repaired with any material which will affect either the taste, odor, color or potability of the water supply when the tank is placed in or returned to service.
F. 
Used piping. Piping which has been used for any other purpose than conveying potable water shall not be used for conveying potable water.
G. 
Connection to boilers and solar hearing units. Potable water connections to boiler feed water systems in which boiler water conditioning chemicals are introduced shall be made through an air gap or provided with an approved backflow preventer located in the potable water line before the point where such chemicals are introduced. Boilers shall be equipped with a check valve in the cold water supply to the boiler.
H. 
Prohibited connections to fixtures and equipment. Connection to the potable water supply system for the following shall be protected against backflow:
(1) 
Bidets.
(2) 
Operating, dissection, embalming, and mortuary tables or similar equipment — in such installation the hose used for water supply shall terminate at least 12 inches away from every point of the table or attachments.
(3) 
Pumps for nonpotable water, chemicals, or other substances — priming connections may be made only through an air gap.
(4) 
Building drainage, sewer or vent systems.
(5) 
Any other fixture of similar hazard.
I. 
Refrigerating unit condensers and cooling jackets. Except where potable water provided for a refrigerator condenser or cooling jacket is entirely outside the piping or tank containing toxic refrigerant, with two separate thickness of metal separating the refrigerant from the potable water supply, inlet connection shall be provided with an approved check valve. Also adjacent to and at the outlet side of the check valve, an approved pressure relief valve set to relieve at five psi above the maximum water pressure at the point of installation shall be provided if the refrigeration units contain more than 20 pounds of refrigerants.
J. 
Used water return prohibited. Except as provided for below, water used for cooling of equipment or other processes shall not be returned to the potable water system. Such water shall be discharged into the drainage system through an air gapped indirect waste. Under conditions where water shortage may occur, the water used for cooling may be used for nonpotable purposes on written approval of the Administrative Authority.
K. 
Protection against backflow and backsiphonage.
(1) 
Water outlets. A potable water system shall be protected against backflow and backsiphonage by providing and maintaining at each outlet:
(a) 
Air gap: An air gap as specified herein between the potable water outlet and the flood level rim of the fixture it supplies or between the outlet and any other source of contamination, or
(b) 
Backflow preventer: A backflow preventer device or vacuum breaker to prevent the drawing of contamination into the potable water system.
(2) 
Minimum required air gap.
(a) 
How measured: The minimum required air gap shall be measured vertically from the lowest end of a potable water outlet to the flood rim or line of the fixture or receptacle into which it discharges.
(b) 
Size: The minimum required air gap shall be twice the effective opening of a potable water outlet unless the outlet is a distance less than three times the effective opening away from a wall or similar vertical surface in which cases the minimum required gap shall be three times the effective opening of the outlet. In no case shall the minimum required air gap be less than shown in Table 860-178K(2), "Minimum Air Gap for Plumbing Fixtures."
Table 860-178K(2)
Minimum Air Gap for Plumbing Fixtures
Minimum Air Gap
Fixture
When Not Affected by Near Wall-1
(inches)
When Affected by Near Wall-2
(inches)
Lavatories and other fixtures with effective opening not greater than 1/2 inch diameter
1.0
1.50
Sink, laundry trays, gooseneck bath faucets and other fixtures with effective opening not greater than 3/4 inch diameter
1.5
2.25
Over rim bath fillers and other fixtures with effective openings not greater that 1 inch diameter
2.0
3.0
Drinking water fountain-single orifice 7/16 (0.437) in diameter or multiple orifices having total area of 0.150 sq. in. (area of circle 7/16 diameter)
1.0
1.50
Effective opening greater than 1 in.
2 x diameter of effective opening
3 x diameter of effective opening
Notes:
1.
Side walls, ribs or similar obstructions do not affect air gaps when spaced from inside edge or spout opening a distance greater than three times the diameter of the effective opening for a single wall, or a distance greater than four times the diameter of the effective opening for two intersecting walls.
2.
Vertical walls, ribs, or similar obstructions extending from the water surface to or above the horizontal plane of the spout opening require a greater air gap when spaced closer to the nearest inside edge of spout opening than specified in Note 1 above. The effect of three or more such vertical walls or ribs has not been determined. In such cases, the air gap shall be measured from the top of the wall.
(3) 
Devices for the Protection of the Potable Water-Supply. Approved backflow preventers or vacuum breakers shall be installed with any plumbing fixture or equipment, the potable water supply outlet of which may be submerged and which cannot be protected by a minimum air gap.
(4) 
Approval of devices. Before any device for the prevention of backflow or backsiphonage is installed, it shall have first been certified by a recognized testing laboratory acceptable to the Administrative Authority. Devices installed in a building potable water supply distribution system for protection against backflow shall be maintained in good working condition by the person or persons responsible for the maintenance of the system. The Administrative Authority having jurisdiction shall routinely inspect such devices and if found to be defective or inoperative shall require the replacement thereof.
(5) 
Installation of devices.
(a) 
Vacuum breakers: Vacuum breakers shall be installed with the critical level at six inches above the flood level rim of the fixture they serve and on the discharge side of the last control-valve to the fixture. No shut-off valve or faucet shall be installed beyond the vacuum breaker. For closed equipment or vessels such as pressure sterilizers the top of the vessel shall be treated as the flood level rim but a check valve shall be installed on the discharge side of the vacuum breaker.
(b) 
Reduced pressure zone backflow preventer: A reduced pressure zone backflow preventer may be installed subject to full static pressure.
(c) 
Devices of all types: Backflow and backsiphonage preventing devices shall be accessibly located preferably in the same room with the fixture they serve. Installation in utility or service spaces, provided they are readily accessible, is also permitted.
(d) 
Hose bibb: With the exception of drain valves all hose bibbs shall be provided with vandal proof vacuum breakers or built in vacuum breakers where applicable.
(6) 
Tanks and vats — below rim supply.
(a) 
Where a potable water outlet terminates below the rim of a tank or vat, and the tank or vat has an overflow of diameter not less than given in Table 860-178B(4), "Sizes of Overflow Pipe for Water Supply Tanks." The overflow pipe shall be provided with an air gap as close to the tank as possible.
(b) 
The potable water outlet to the tank or vat shall terminate a distance not less than 1 1/2 times the height to which water can rise in the tank above the top of the overflow. This level shall be established at the maximum flow rate of the supply to the tank or vat and with all outlets except the air gap, overflow outlet closed.
(7) 
Protective devices required. Approved devices to protect against backflow and backsiphonage shall be installed at all fixtures and equipment where backflow and/or siphonage may occur and where a minimum air gap cannot be provided between the water outlet to the fixture or equipment and its flood level rim.
(a) 
Connections not subject to back pressure: Where a water connection is not subject to back pressure, a non-pressure type vacuum breaker shall be installed on the discharge side of the last valve on the line serving the fixture or equipment. A list of some conditions requiring protective devices of this kind is given in Table 860-179K(7), "A Cross Connection where Protective Devices are Required and Critical level (C-L) Settings for Backflow Preventers."
Table 860-179K(7)(a)
Cross Connections where Protective Devices are Required and Critical Level (C-L) Settings for Backflow Preventers1
Fixture or Equipment
Method of Installation
Aspirators and ejectors
C-L at least 6 inches above flood level of receptacle.
Dental units
On models without built-in vacuum breakers — C-L at least 6" above flood level rim of bowl.
Dishwashing machines
C-L at least 6" above flood level of machine. Install on both hot and cold supply lines.
Flushometers (closet and urinal)
C-L at least 6" above top of fixture supplied.
Garbage can cleaning machine
C-L at least 6" above flood level of machines. Install on both hot and cold supply lines.
Hose outlets
C-L at least 6" above highest point on hose line.
Laundry machines
C-L at least 6" above flood level of machines. Install on both hot and cold supply lines.
Lawn Sprinklers
C-L at least 12" above highest sprinkler or discharge outlet.
Steam tables
C-L at least 6" above flood level.
Tanks and Vats
C-L at least 6" above flood level rim or line.
Trough urinals
C-L at least 6" above perforated flush pipe.
Flush tanks
Equip with approved ball cock. Where ball cocks touch tank water equip with vacuum breaker at least 1" above overflow outlets. Where ball cock does not touch tank water install ball cock outlet at least 1" above overflow outlet or provide vacuum breaker as specified above.
Hose bibs (where aspirators or ejectors could be connected)
C-L at least 6" above flood level of receptacle served.
NOTE:
1.
Critical level (C-L) is defined as the level to which the backflow preventer (vacuum breaker) may be submerged before backflow will occur. Where the C-L is not shown on the preventer, the bottom of the device shall be taken as the C-L.
(b) 
Connections Subject to Back Pressure: Where a potable water connection is made to a line, fixture, tank, vat, pump or other equipment with a hazard of backflow or backsiphonage where the water connection is subject to backpressure, and an air gap or backflow preventer cannot be installed, the Administrative Authority may require the use of an approved reduced pressure zone backflow preventer and, also, in extreme situations, an approved pressure type vacuum breaker. A partial list of such connections is shown in Table 860-179K(7)(b), "Partial List of Cross Connections Subject to Back Pressure."
Table 860-179K(7)(b)
Partial List of Cross Connections Subject to Back Pressure
Chemical Lines
Dock Water Outlets
Individual Water Supplies
Industrial Process Water Lines
Pressure Tanks
Pumps
Steam Lines
Swimming Pools
Tanks and Vats — Bottom Inlets
Hose Bibs
Carbonated Beverage Dispensers
(8) 
Barometric loop. Water connections not subject to back pressure where an actual or potential backflow or backsiphonage hazard exist may in lieu of devices specified in Subsection K(7) be provided with a barometric loop. Barometric loops shall precede the point of connection.
In residences and buildings intended for continuous occupancy, hot water shall be supplied to all plumbing fixtures and equipment used for bathing, washing, culinary purpose, cleansing, laundry, or building maintenance, with sufficient capacity to insure a minimum of 110° F.
A. 
Return circulation — where required. Hot water supply systems in four-story buildings or buildings where the developed length of hot water piping from the source of hot water supply to the farthest fixture supplied exceeds 100 feet shall be of the return circulation type. (Raychem Hwat System is an acceptable alternate.)
B. 
Water pressure relief valves and temperature relief valves required.
(1) 
Safety devices.
(a) 
Equipment used for heating water or storing hot water shall be protected by approved safety devices in accordance with one of the following methods:
[1] 
A separate pressure relief valve and a separate temperature relief valve; or
[2] 
A combination pressure and temperature relief valve;
[3] 
Except that tankless heaters installed on low pressure steam or hot water heating boilers shall have a pressure relief valve installed as well as a water mixing or tempering valve to limit the water temperature to domestic fixtures to not over 140° F.
(b) 
All safety devices shall meet the current requirements of the United States of America Standards Institute, American Society of Mechanical Engineers, or the Underwriters Laboratories. Listing by Underwriters Laboratories, American Gas Association, or National Board of Boiler and Pressure Vessel Inspectors shall constitute evidence of conformance with these standards. Where a device is not listed by any of these, it must have certification by an approved laboratory as having met these requirements.
(2) 
Pressure relief valves. Pressure relief valves shall meet the requirements of the current USAFI Standards and where required by the Inspection Authorities also the ASME code requirements. The valves shall have an official rating not less than the rating of the heater or heaters on which they are installed. They shall be set at a pressure not in excess of the listed working pressure of the tank or vessel. Pressure relief valves shall be installed directly on the tank or heater in the hot water outlet.
(3) 
Temperature relief valves. Temperature relief valves shall have official and listed capacity of not less than the input rating of the heater or heaters on which they are installed. They shall be installed so that the temperatures sensing element is immersed in the hottest water within the top six inches of the tank. The valve shall be set to open when the stored temperature is 210° F. (or less).
(4) 
Combination pressure — temperature relief valves. Combination pressure — temperature relief valves shall comply with the requirements for both pressure and temperature relief valves.
(5) 
Installation of relief valves. No check valve or shut-off valve shall be installed between any safety device and the hot water equipment used, nor shall there be any shut-off valve in the discharge pipe from the relief valve. The discharge pipe shall not be smaller at any point than the discharge pipe size connection of the relief valve and shall pitch downward to its termination with no water pockets being permitted throughout its full length. Relief outlets when connected to the building drainage system shall be indirectly connected.
C. 
Pressure marking of hot water storage tank. Hot water storage tanks shall be permanently marked in an accessible place with the maximum allowable working pressure.
D. 
Drain cocks or valves for hot water storage tanks. Drain cocks or valves for emptying shall be installed at the lowest point of each water storage tank.
E. 
Scald proof tub and shower valves. All new or replaced shower and tub-shower combinations shall be provided with individual control valves of the pressure balance or thermostatic mixing type or other approved device. Such valves shall be equipped with high- limit stops adjusted to a maximum hot water setting of 120° F. Multiple or gang showers may be controlled by a master thermostatic mixing valve set to limit the hot water temperature to a maximum of 120° F.
F. 
Thermal expansion control. Installed closed domestic hot water piping systems shall be provided with approved means to control thermal expansion.