Plumbing Systems

24 C.F.R. Part ..., Subpart G
in effectEffective: 2024-07-01

24 C.F.R. § 3280.601 Scope.

Subpart G of this standard covers the plumbing materials, fixtures, and equipment installed within or on manufactured homes. It is the intent of this subpart to assure water supply, drain, waste and vent systems which permit satisfactory functioning and provide for health and safety under all conditions of normal use.

24 C.F.R. § 3280.602 Definitions.

The following definitions are applicable to subpart G only: Accessible, when applied to a fixture, connection, appliance or equipment, means having access thereto, but which may require removal of an access panel or opening of a door. Air gap (water distribution system) means the unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture, water supplied appliances, or other device and the flood level rim of the receptacle. Backflow means the flow of water or other liquids, mixtures, or substances into the distributing pipes of a potable supply of water from any source or sources other than its intended sources. Backflow connection means any arrangement whereby backflow can occur. Backflow preventer means a device or means to prevent backflow. Branch means any part of the piping system other than a riser, main or stack. Common vent means a vent connecting at the junction of fixture drains and serving as a vent for more than one fixture. Continuous vent means a vertical vent that is a continuation of the drain to which it connects. Continuous waste means a drain from two or more fixtures connected to a single trap. Critical level means a point established by the testing laboratory (usually stamped on the device by the manufacturer) which determines the minimum elevation above the flood level rim of the fixture or receptacle served on which the device may be installed. When a backflow prevention device does not bear a critical level marking, the bottom of the vacuum breaker, combination valve, or of any such approved or listed device shall constitute the critical level. Cross connection means any physical connection or arrangement between two otherwise separate systems or sources, one of which contains potable water and the other either water, steam, gas or chemical of unknown or questionable safety whereby there may be a flow from one system or source to the other, the direction of flow depending on the pressure differential between the two systems. Developed length means that length of pipe measured along the center line of the pipe and fittings. Diameter, unless otherwise specifically stated, means the nominal (inside) diameter designated commercially. Drain means a pipe that carries waste, water, or water-borne waste in a drainage system. Drain connector means the removable extension, consisting of all pipes, fittings and appurtenances, from the drain outlet to the drain inlet serving the manufactured home. Drain outlet means the lowest end of the main or secondary drain to which a sewer connection is made. Drainage system means all piping within or attached to the structure that conveys sewage or other liquid waste to the drain outlet, not including the drain connector. Fixture drain means the drain from the trap of a fixture to the junction of that drain with any other drain pipe. Fixture supply means the water supply pipe connecting a fixture to a branch water supply pipe or directly to a main water supply pipe. Flood-level means the level in the receptacle over which water would overflow to the outside of the receptacle. Flooded means the condition which results when the liquid in a container or receptacle rises to the flood-level. Flush tank means that portion of a water closet that is designed to contain sufficient water to adequately flush the fixture. Flush valve means a device located at the bottom of a flush tank for flushing a water closet. Flushometer tank: means a device integrated within an air accumulator vessel which is designed to discharge a predetermined quantity of water to fixtures for flushing purposes. Flushometer valve means a device which discharges a predetermined quantity of water to a fixture for flushing purposes and is closed by direct water pressure. Grade means the fall (slope) of a pipe in reference to a horizontal plane expressed in inches per foot length. Horizontal branch means any pipe extending laterally, which receives the discharge from one or more fixture drains and connects to the main drain. Horizontal pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the horizontal. Indirect waste receptor means a receptor that receives a discharge waste pipe that is not directly connected to a receptor but maintains a suitable air gap between the end of the pipe and the top of the drain. Individual vent means a pipe installed to vent a fixture drain. Inlet coupling means the terminal end of the water system to which the water service connection is attached. It may be a swivel fitting or threaded pipe end. Main means the principal artery of the system to which branches may be connected. Main drain means the lowest pipe of a drainage system which receives sewage from all the fixtures within a manufactured home and conducts these wastes to the drain outlet. Main vent means the principal artery of the venting system to which vent branches may be connected. Mechanical trap vent device means a device that automatically opens to admit air to a fixture drain above the connection of the trap arm so as to prevent siphonage, and closes tightly when the pressure within the drainage system is equal to or greater than atmospheric pressure, so as to prevent the escape of gases from the drainage system into the manufactured home. Offset means a combination of pipe and/or fittings that brings one section of the pipe out of line but into a line parallel with the other section. Pitch. See Grade. Plumbing appliance: means any one of a special class of plumbing fixture which is intended to perform a special plumbing function. Its operation and/or control may be dependent upon one or more energized components, such as motors, control, heating elements, or pressure or temperature-sensing elements. Such fixture may operate automatically through one or more of the following actions: A time cycle, a temperature range, a pressure range, a measured volume or weight, or the fixture may be manually adjusted or controlled by the user or operator. Plumbing appurtenance: means a manufactured device, or a prefabricated assembly, or an on-the-job assembly of component parts, and which is an adjunct to the basic piping system and plumbing system and plumbing fixtures. An appurtenance demands no additional water supply, nor does it add any discharge load to a fixture or the drainage system. Plumbing fixtures means receptacles, devices, or appliances which are supplied with water or which receive liquid or liquid-borne wastes for discharge into the drainage system. Plumbing system means the water supply and distribution pipes; plumbing fixtures, faucets and traps; soil, waste and vent pipes; and water-treating or water-using equipment. Primary vent. See main vent. Relief vent means an auxiliary vent which permits additional circulation of air in or between drainage and vent systems. Secondary vent means any vent other than the main vent or those serving each toilet. Sewage means any liquid waste containing animal or vegetable matter in suspension or solution, and may include liquids containing chemicals in solution. Siphonage means the loss of water seal from fixture traps resulting from partial vacuum in the drainage system which may be of either of the following two types, or a combination of the two: (a) Self-siphonage resulting from vacuum in a fixture drain generated solely by the discharge of the fixture served by that drain, or, (b) Induced siphonage resulting from vacuum in the drainage system generated by the discharge of one or more fixtures other than the one under observation. Trap means a fitting or device designed and constructed to provide a liquid seal that will prevent the back passage of air without materially affecting the flow of liquid waste through it. Trap arm means the portion of a fixture drain between a trap and its vent. Trap seal means the vertical depth of liquid that a trap will retain. Vacuum breaker. See backflow preventer. Vent cap means the device or fitting which protects the vent pipe from foreign substance with an opening to the atmosphere equal to the area of the vent it serves. Vent system means that part of a piping installation which provides circulation of air within a drainage system. Vertical pipe means any pipe or fitting which makes an angle of not more than 45 degrees with the vertical. Water closet drain means that part of the drainage piping which receives the discharge from each individual water closet. Water connection means the fitting or point of connection for the manufactured home water distribution system designed for connection to a water supply. Water connector means the removable extension connecting the manufactured home water distribution system to the water supply. Water distribution system means potable water piping within or permanently attached to the manufactured home. Wet vent means a vent which also serves as a drain for one or more fixtures. Wet vented drainage system means the specially designed system of drain piping that also vents one or more plumbing fixtures by means of a common waste and vent pipe. Whirlpool bathtub means a plumbing appliance consisting of a bathtub fixture which is equipped and fitted with a circulation piping system, pump, and other appurtenances and is so designed to accept, circulate, and discharge bathtub water upon each use.

24 C.F.R. § 3280.603 General requirements.

(a) Minimum requirements. Any plumbing system installed in a manufactured home shall conform, at least, with the provisions of this subpart. (1) General. The plumbing system shall be of durable material, free from defective workmanship, and so designed and constructed as to give satisfactory service for a reasonable life expectancy. (2) Conservation. Each water closet must not use more than 1.6 gallons of water per flush. (3) Connection to drainage system. All plumbing, fixtures, drains, appurtenances, and appliances designed or used to receive or discharge liquid waste or sewage shall be connected to the manufactured home drainage system in a manner provided by this standard. (4) Workmanship. All design, construction, and workmanship shall be in conformance with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this standard. (5) Components. Plumbing materials, devices, fixtures, fittings, equipment, appliances, appurtenance, and accessories intended for use in or attached to a manufactured home shall conform to one of the applicable standards referenced in § 3280.604. Where an applicable standard is not referenced, or an alternative recognized standard is utilized, the plumbing component shall be listed by a nationally recognized testing laboratory, inspection agency or other qualified organization as suitable for the intended use. (6) Prohibited fittings and practices. (i) Drainage or vent piping shall not be drilled and tapped for the purpose of making connections. (ii) Except as specifically provided elsewhere in this standard, vent pipes shall not be used as waste or drain pipes. (iii) Fittings, connections, devices, or methods of installation that obstruct or retard the flow of sewage, or air in the drainage or venting systems in an amount greater than the normal frictional resistance to flow shall not be used unless their use is acceptable in this standard or their use is accepted as having a desirable and acceptable function of ultimate benefit to the proper and continued functioning of the plumbing system. (iv) Cracks, holes, or other imperfections in materials shall not be concealed by welding, brazing, or soldering or by paint, wax, tar, or other leak-sealing or repairing agents. (v) Piping, fixtures or equipment shall be located so as not to interfere with the normal use or with the normal operation and use of windows, doors or other required facilities. (vi) Galvanized pipe shall not be bent or welded. (7) Alignment of fittings. All valves, pipes, and fittings shall be installed in correct relationship to the direction of flow. (b) Protective requirements. (1) Cutting structural members. Structural members shall not be unnecessarily or carelessly weakened by cutting or notching. (2) Exposed piping. All piping, pipe threads, hangers, and support exposed to the weather, water, mud, and road hazard, and subject to damage therefrom, shall be painted, coated, wrapped, or otherwise protected from deterioration. (3) Road damage. Pipes, supports, drains, outlets, or drain hoses shall not extend or protrude in a manner where they could be unduly subjected to damage during transit. (4) Freezing. All piping and fixtures subject to freezing temperatures shall be insulated or protected to prevent freezing, under normal occupancy. The manufacturer shall provide: (i) Written installation instructions for the method(s) required for compliance to this section; (ii) A statement in the installation instructions required by § 3280.306(b), stating that if the heat tape or pipe heating cable is used, it must be listed for use with manufactured homes. (iii) A receptacle outlet complying with § 3280.806(d)(10). (5) All piping, except the fixture trap, shall be designed to allow drainage. (6) Rodent resistance. All exterior openings around piping and equipment shall be sealed to resist the entrance of rodents. (7) Piping and electrical wiring shall not pass through the same holes in walls, floors or roofs. Plastic piping shall not be exposed to heat in excess of manufacturers recommendation or radiation from heat producing appliances.

24 C.F.R. § 3280.604 Materials.

(a) Minimum standards. Materials, devices, fixtures, fittings, equipment, appliances, appurtenances and accessories shall conform to one of the standards in the following table and be free from defects. Where an appropriate standard is not indicated in the table or a standard not indicated in the table is preferred, the item may be used if it is listed. A listing is also required when so specified in other sections of this subpart. (b) Where more than one standard is referenced for a particular material or component, compliance with only one of those standards is acceptable. Exceptions: (1) When one of the reference standards requires evaluation of chemical, toxicity or odor properties which are not included in the other standard, then conformance to the applicable requirements of each standard shall be demonstrated; (2) When a plastic material or component is not covered by the Standards in the following table, it must be certified as non-toxic in accordance with ANSI/NSF 61-2001, Drinking water system components—Health effects. Ferrous Pipe and Fittings Gray Iron Threaded Fittings—ANSI/ASME B16.4-1992. Malleable Iron Threaded Fittings—ANSI/ASME B16.3-1992. Material and Property Standard for Special Cast Iron Fittings—IAPMO PS 5-84. Welding and Seamless Wrought Steel Pipe—ANSI/ASME B36.10-1979. Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless—ASTM A53-93. Pipe Threads, General Purpose (Inch)—ANSI/ASME B1.20.1-1983. Standard Specification for Cast Iron Soil Pipe and Fittings—ASTM A74-92. Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications—CISPI-301-90. Nonferrous Pipe and Fittings Standard Specification for Seamless Copper Pipe, Standard Sizes—ASTM B42-93. Standard Specification for General Requirements for Wrought Seamless Copper and Copper-Alloy Tube—ASTM B251-93. Standard Specification for Seamless Copper Water Tube—ASTM B88-93. Standard Specification for Copper Drainage Tube (DWV)—ASTM B306-92. Wrought Copper and Copper Alloy Solder-Joint Pressure Fitting—ASME/ANSI B16.22-1989. Wrought Copper and Wrought Copper Alloy Solder-Joint Drainage Fittings-DWV—ASME/ANSI B16.29-1986. Cast Copper Alloy Solder-Joint Pressure Fittings—ANSI B16.18-1984. Cast Copper Alloy Solder-Joint Drainage Fittings-DWV—ASME B16.23-1992. Cast Copper Alloy Fittings for Flared Copper Tubes—ASME/ANSI B16.26-1988. Standard Specification for Seamless Red Brass Pipe, Standard Sizes—ASTM B43-91. Cast Bronze Threaded Fittings, Classes 125 and 250—ANSI/ASME B16.15-1985. Plastic Pipe and Fittings Standard Specification Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe and Fittings—ASTM D2661-91. Standard Specification for Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings—ASTM D2665-91b. Standard Specification for Drain, Waste, and Vent (DWV) Plastic Fittings Patterns—ASTM D3311-92. Standard Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40, Plastic Drain, Waste, and Vent Pipe With a Cellular Core—ASTM F628-91. Standard Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Hot- and Cold-Water Distribution Systems—ASTM D2846-92. Standard Specification for Polybutylene (PB) Plastic Hot- and Cold-Water Distribution Systems—ASTM D3309-92a. Plastic Piping Components and Related Materials—ANSI/NSF 14-1990. Standard Specification for Crosslinked Polyethylene (PEX) Tubing—ASTM F876-10 (incorporated by reference, see § 3280.4). Standard Specification for Crosslinked Polyethylene (PEX) Plastic Hot- and Cold-Water Distribution Systems—ASTM F877-07 (incorporated by reference, see § 3280.4). Miscellaneous Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings, ASTM C564-97 (incorporated by reference, see § 3280.4). Backflow Valves—ANSI A112.14.1-1975. Plumbing Fixture Setting Compound—TTP 1536A-1975. Material and Property Standard for Cast Brass and Tubing P-Traps—IAPMO PS 2-89. Relief Valves for Hot Water Supply Systems, ANSI Z21.22-1999 (incorporated by reference, see § 3280.4). Standard Specification for Solvent Cement for Acrylonitrile-Butadiene-Styrene (ABS) Plastic Pipe and Fittings—ASTM D2235-88. Standard Specification for Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic Piping Systems—ASTM D2564-91a. Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings—CISPI-HSN-85. Plumbing System Components for Manufactured Homes and Recreational Vehicles—ANSI/NSF 24-1988. Material and Property Standard for Diversion Tees and Twin Waste Elbow—IAPMO PS 9-84. Material and Property Standard for Flexible Metallic Water Connectors—IAPMO PS 14-89. Material and Property Standard for Dishwasher Drain Airgaps—IAPMO PS 23-89. Material and Property Standards for Backflow Prevention Assemblies—IAPMO PS 31-91. Performance Requirements for Air Admittance Valves for Plumbing Drainage Systems, Fixture and Branch Devices—ASSE Standard #1051, 1990 Revised: 1996/ANSI 1998. Drinking Water System Components-Health Effects—ANSI/NSF 61-2001. Plumbing Fixtures Plumbing Fixtures (General Specifications)—FS WW-P-541E/GEN-1980. Vitreous China Plumbing Fixtures—ANSI/ASME A112.19.2(M)-1990. Enameled Cast Iron Plumbing Fixtures—ANSI/ASME A112.19.1M-1987. Porcelain Enameled Formed Steel Plumbing Fixtures—ANSI/ASME A112.19.4(M)-1984. Plastic Bathtub Units with Addenda Z124.1a-1990 and Z124.16-1991—ANSI Z124.1-1987. Standard for Porcelain Enameled Formed Steel Plumbing Fixtures—IAPMO TSC 22-85. Plastic Shower Receptors and Shower Stalls with Addendum Z124.2a-1990—ANSI Z124.2-1987. Stainless Steel Plumbing Fixtures (Designed for Residential Use)—ANSI/ASME A112.19.3M-1987. Material and Property Standard for Drains for Prefabricated and Precast Showers—IAPMO PS 4-90. Plastic Lavatories with Addendum Z124.3a-1990—ANSI Z124.3-1986. Standard for Safety Glazing Materials used in Buildings—Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4). Water Heater Relief Valve Drain Tubes—ASME A112.4.1-1993. Flexible Water Connectors—ASME A112.18.6-1999. Performance Requirements for Backflow Protection Devices and Systems in Plumbing Fixture Fittings—ASME A112.18.3M-1996. Non-Vitreous Ceramic Plumbing Fixtures—ASME A112.19.9M-1991. Dual Flush Devices for Water Closets—ASME A119.19.10-1994. Deck Mounted Bath/Shower Transfer Valves with Integral Backflow Protection—ASME A112.18.7-1999. Plastic Fittings for Connecting Water Closets to the Sanitary Drainage System—ASME A112.4.3-1999. Hydraulic Performance Requirements for Water Closets and Urinals, ASME A112.19.6-1995. Plumbing Fixture Fittings—ASME/ANSI A112.18.1M-1989. Trim for Water Closet, Bowls, Tanks, and Urinals—ANSI A112.19.5-1979. Plastic Water Closets, Bowls, and Tanks with Addenda Z124.4a-1990—ANSI Z124.4-1986. ANSI Z124.5, Plastic Toilet (Water Closets) Seats, 1997. ANSI Z124.7, Prefabricated Plastic Spa Shells, 1997. Whirlpool Bathtub Appliances—ASME/ANSI A112.19.7M-1987. ANSI Z-124.9, Plastic Urinal Fixtures, 1994. Performance Requirements for Individual Thermostatic Pressure Balancing and Combination Control for Bathing Facilities—ASSE 1016-1988 (ANSI 1990). Performance Requirements for Pressurized Flushing Devices (Flushometers) for Plumbing Fixtures—ASSE 1037-1990 (ANSI-1990). Performance Requirements for Water Closet Flush Tank Fill Valves (Ballcocks)—ASSE 1002 Revision 5-1986 (ANSI/ASSE-1979). Performance Requirements for Hand-held Showers—ASSE 1014-1989 (ANSI-1990). Hydrants for Utility and Maintenance Use—ANSI/ASME A112.21.3M-1985. Performance Requirements for Home Laundry Equipment—ASSE 1007-1986. Performance Requirements for Hot Water Dispensers, Household Storage Type Electrical—ASSE 1023, (ANSI/ASSE-1979). Plumbing Requirements for Residential Use (Household) Dishwashers—ASSE 1006, (ASSE/ANSI-1986). Performance Requirements for Household Food Waste Disposer Units—ASSE 1008-1986. Performance Requirements for Temperature Activated Mixing Valves for Primary Domestic Use—ASSE 1017-1986. Water Hammer Arresters—ANSI A112.26.1-1969 (R 1975). Suction Fittings for Use in Swimming Pools, Wading Pools, Spas, Hot Tubs, and Whirlpool Bathtub Appliances—ASME/ANSI A112.19.8M-1989. Air Gaps in Plumbing Systems—ASME A112.1.2-1991. Performance Requirements for Diverters for Plumbing Faucets with Hose Spray, Anti-Siphon Type, Residential Applications—ASSE 1025 (ANSI/ASSE-1978). Performance Requirements for Pipe Applied Atmospheric Type Vacuum Breakers—ASSE 1001 (ASSE/ANSI-1990). Performance Requirements for Hose Connection Vacuum Breakers—ASSE 1011-1981 (ANSI-1982). Performance Requirements for Wall Hydrants, Frost Proof Automatic Draining, Anti-Backflow Types—ANSI/ASSE 1019-1978. Performance Requirements for Automatic Compensating Values for Individual Shower and Tub/Shower Combinations, approved January 2005 ASSE 1016-2005 (incorporated by reference, see § 3280.4). Performance Requirements for Water Temperature Limiting Devices, approved February 2004, ASSE 1070-2004 (incorporated by reference, see § 3280.4).

24 C.F.R. § 3280.605 Joints and connections.

(a) Tightness. Joints and connections in the plumbing system shall be gastight and watertight for the pressures required under testing procedures. (b) Assembling of pipe. All joints and connections shall be correctly assembled for tightness. Pipe threads shall be fully engaged with the threads of the fitting. Plastic pipe and copper tubing shall be inserted to the full depth of the solder cup or welding sockets of each fitting. Pipe threads and slip joints shall not be wrapped with string, paper, putty, or similar fillers. (c) Threaded joints. Threads for screw pipe and fittings shall conform to the approved or listed standard. Pipe ends shall be reamed out to size of bore. All burrs, chips, cutting oil and foreign matter shall be removed. Pipe joint cement or thread lubricant shall be of approved type and applied to male threads only. (d) Solder joints. Solder joints for tubing shall be made with approved or listed solder type fittings. Surfaces to be soldered shall be cleaned bright. The joints shall be properly fluxed with noncorrosive paste type flux and, for manufactured homes to be connected to a public water system, made with solder having not more than 0.2 percent lead. (e) Plastic pipe, fittings and joints. Plastic pipe and fittings shall be joined by installation methods recommended by the manufacturer or in accordance with the provisions of a recognized, approved, or listed standard. (f) Union joints. Metal unions in water piping shall have metal-to-metal ground seats. (g) Flared joints. Flared joints for soft-copper water tubing shall be made with approved or listed fittings. The tubing shall be expanded with a proper flaring tool. (h) Cast iron soil pipe joints. Approved or listed cast iron pipe may be joined as follows: (1) Approved or listed hub-less pipe and fittings must be permitted to be joined with listed couplings or adapters, per the manufacturer's recommendations. (2) Hub and plain-end soil pipe may be joined by compression fittings per the manufacturer's recommendation.

24 C.F.R. § 3280.606 Traps and cleanouts.

(a) Traps—(1) Traps required. Each plumbing fixture, except listed toilets, shall be separately trapped by approved water seal “P” traps. All traps shall be effectively vented. (2) Combination Fixtures. For the purposes of drainage and ventilation requirements, a two- or three-compartment sink, up to three single sinks, or up to three lavatories may be connected to one “P” trap and considered as a single fixture, so long as the sinks and lavatories are in the same room, have waste outlets not more than 30 inches apart, and have flood level rims at the same level. The “P” trap must be installed at the center fixture when three such fixtures are installed. (3) Prohibited traps. A trap which depends for its seal upon concealed interior partitions shall not be used. Full “S” traps, bell traps, drum traps, crown-vented traps, and running traps are prohibited. Fixtures shall not be double-trapped. (4) Material and design. Each trap shall be self-cleaning with a smooth and uniform interior waterway. Traps shall be manufactured of cast iron, cast brass, or drawn brass tubing of not less than No. 20 Brown and Sharpe gage, or approved or listed plastic, or other approved or listed material. Union joints for a trap shall be beaded to provide a shoulder for the union nut. Each trap shall have the manufacturer's name stamped or cast in the body of the trap, and each tubing trap shall show the gage of the tubing. (5) Trap seal. Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal. (6) Size. Traps shall be not less than 1 1/4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected. (7) Location. Each trap shall be located as close to its vent and to its fixture outlet as structural conditions will permit. (8) Length of tailpiece. The vertical distance from a trap to the fixture outlet shall not exceed 24 inches. (9) Installation. (i) Grade of trap arm. The piping between a “P” trap and the fixture tee or the vented waste line shall be graded 1/4 inch per foot towards the vent and in no event shall have a slope greater than its diameter. The vent opening at fixture tees shall not be below the weir of the “P” trap outlet. (ii) Trap arm offset. The piping between the “P” trap and vent may change direction or be offset horizontally with the equivalent of no more than 180 degrees total change in direction with a maximum of 90 degrees by any one fitting. (iii) Concealed traps. Traps with mechanical joints shall be accessible for repair and inspection. (iv) Removability of traps, etc. Traps shall be designed and installed so the “U” bend is removable without removing the strainers from the fixture. Continuous waste and tail pieces which are permanently attached to the “U” bend shall also be removable without removing the strainer from the fixture. (b) Cleanout openings—(1) Location of cleanout fittings. (i) Cleanouts shall be installed if the drainage system cannot be cleaned through fixtures, drains, or vents. Cleanouts shall also be provided when fittings of more than 45 degrees are used to affect an offset except where long turn ells are used which provide sufficient “sweep” for cleaning. (ii) A full size cleanout shall be installed at the upper end of any section of drain piping which does not have the required minimum slope of 1/4 inch per foot grade. (iii) A cleaning tool shall not be required to pass through more than 360 degrees of fittings, excluding removable “P” traps, to reach any part of the drainage system. Water closets may be removed for drainage system access. (2) Access to cleanouts. Cleanouts shall be accessible through an unobstructed minimum clearance of 12 inches directly in front of the opening. Each cleanout fitting shall open in a direction opposite to the flow or at right angles to the pipe. Concealed cleanouts that are not provided with access covers shall be extended to a point above the floor or outside of the manufactured home, with pipe and fittings installed, as required, for drainage piping without sags and pockets. (3) Material. Plugs and caps shall be brass or approved or listed plastic, with screw pipe threads. (4) Design. Cleanout plugs shall have raised heads except that plugs at floor level shall have counter-sunk slots.

24 C.F.R. § 3280.607 Plumbing fixtures.

(a) General requirements—(1) Quality of fixtures. Plumbing fixtures shall have smooth impervious surfaces, be free from defects and concealed fouling surfaces, be capable of resisting road shock and vibration, and shall conform in quality and design to listed standards. Fixtures shall be permanently marked with the manufacturer's name or trademark. (2) Strainers. The waste outlet of all plumbing fixtures, other than toilets, shall be equipped with a drain fitting that will provide an adequate unobstructed waterway. (3) Fixture Connections. Fixture tailpieces and continuous wastes in exposed or accessible locations must be of not less than No. 20 Brown and Sharpe gauge seamless drawn-brass tubing or other approved pipe or tubing materials. Inaccessible fixture connections must be constructed according to the requirements for drainage piping. The diameter of each fixture tailpiece, continuous waste, or waste and overflow must be not less than: (i) 1 1/2 inches, for sinks of two or more compartments, dishwashers, clothes washing machines, laundry tubs, bathtubs, and showers; and (ii) Not less than 1 1/4 inches for lavatories or single compartment sinks having a 2-inch maximum drain opening. (4) Concealed connections. Concealed slip joint connections shall be provided with adequately sized unobstructed access panels and shall be accessible for inspection and repair. (5) Directional fitting. An approved or listed “Y” or other directional-type branch fitting shall be installed in every tailpiece or continuous waste that receives the discharge from food waste disposal units, dishwashing, or other force-discharge fixture or appliance. (See also § 3280.607(b)(4)(ii).) (6) Water conservation. All lavatory faucets, showerheads, and sink faucets must not exceed a flow of 2.5 gallons per minute (gpm). (b) Fixtures—(1) Spacing. All plumbing fixtures shall be so installed with regard to spacing as to be reasonably accessible for their intended use. (2) Water closets. (i) Water closets shall be designed and manufactured according to approved or listed standards and shall be equipped with a water flushing device capable of adequately flushing and cleaning the bowl at each operation of the flushing mechanism. (ii) Water closet flushing devices shall be designed to replace the water seal in the bowl after each operation. Flush valves, flushometer valves, flushometer tanks and ballcocks shall operate automatically to shut off at the end of each flush or when the tank is filled to operating capacity. (iii) All water closets must be low consumption (1.6 gallons per flush (gpf)) closets. (iv) Flush tanks shall be fitted with an overflow pipe large enough to prevent flooding at the maximum flow rate of the ball cock. Overflow pipes shall discharge into the toilet, through the tank. (v) Floor Connection. Water closets must be securely bolted to an approved flange or other approved fitting that is secured to the floor by means of corrosion-resistant screws. The bolts must be of solid brass or other corrosion-resistant material and must not be less than 1/4 inch in diameter. A watertight seal must be made between the water closet and flange or other approved fitting by use of a gasket, sealing compound, or listed connector device. (vi) Floor connection. Water closets shall be securely bolted to an approved flange or other approved fitting which is secured to the floor by means of corrosion-resistant screws. The bolts shall be of solid brass or other corrosion-resistant material and shall be not less than one-fourth inch in diameter. A watertight seal shall be made between the water closet and flange or other approved fitting by use of a gasket or sealing compound. (3) Shower compartment. (i) Each compartment stall shall be provided with an approved watertight receptor with sides and back extending at least 1 inch above the finished dam or threshold. In no case shall the depth of a shower receptor be less than 2 inches or more than 9 inches measured from the top of the finished dam or threshold to the top of the drain. The wall area shall be constructed of smooth, noncorrosive, and nonabsorbent waterproof materials to a height not less than 6 feet above the bathroom floor level. Such walls shall form a watertight joint with each other and with the bathtub, receptor or shower floor. The floor of the compartment shall slope uniformly to the drain at not less than one-fourth nor more than one-half inch per foot. (ii) The joint around the drain connection shall be made watertight by a flange, clamping ring, or other approved listed means. (iii) Shower doors and tub and shower enclosures shall be constructed so as to be waterproof and, if glazed, glazing shall comply with the Standard for Safety Glazing Materials used in Buildings—Safety Performance Specifications and Methods of Test, ANSI Z97.1-2004 (incorporated by reference, see § 3280.4). (iv) Prefabricated plumbing fixtures shall be approved or listed. (v) Shower and tub-shower combination valves must be balanced pressure, thermostatic, or combination mixing valves that conform to the requirements of ASSE 1016-2005, Performance Requirements for Automatic Compensating Valves for Individual Shower and Tub/Shower Combinations (incorporated by reference, see § 3280.4). Such valves must be equipped with handle position stops that are adjustable in accordance with the valve manufacturer's instructions and to a maximum setting of 120 °F. Hot water supplied to bathtubs and whirlpool bathtubs are to be limited to a temperature of not greater than 120 °F by a water temperature limiting device that conforms to the requirements of ASSE 1070-2004, Performance Requirements for Water Temperature Limiting Devices (incorporated by reference, see § 3280.4). (4) Dishwashing machines. (i) A dishwashing machine must discharge its waste through a fixed air gap installed above the machine, through a high loop as specified by the dishwashing machine manufacturer, or into an open standpipe receptor with a height greater than the washing compartment of the machine. When a standpipe is used, it must be at least 18 inches, but not more than 30 inches, above the trap weir. The drain connections from the air gap or high loop are permitted to connect to an individual trap to a directional fitting installed in the sink tailpiece or to an opening provided on the inlet side of a food waste disposal unit. (ii) Drain from a dishwashing machine shall not be connected to a sink tailpiece, continuous waste line, or trap on the discharge side of a food waste disposal unit. (5) Clothes washing machines. (i) Clothes washing machines shall drain either into a properly vented trap, into a laundry tub tailpiece with watertight connections, into an open standpipe receptor, or over the rim of a laundry tub. (ii) Standpipes must be either 1 1/2 inch diameter minimum nominal iron pipe size, 1 1/2 inch diameter nominal brass tubing of not less than No. 20 Brown and Sharp gauge, or 1 1/2 inch diameter approved plastic materials. Receptors must discharge into a vented trap or must be connected to a laundry tub appliance by means of an approved or listed directional fitting. Each standpipe must extend not less than 18 inches or more than 42 inches above its trap and must terminate in an accessible location no lower than the top of the clothes washing machine. A removable, tight-fitting cap or plug must be installed on the standpipe when the clothes washer is not provided. (iii) Clothes washing machine drain shall not be connected to the tailpiece, continuous waste, or trap of any sink or dishwashing machine. (c) Installation—(1) Access. Each plumbing fixture and standpipe receptor shall be located and installed in a manner to be accessible for usage, cleaning, repair and replacement. Access to diverter valves and other connections from the fixture hardware is not required. (2) Alignment. Fixtures shall be set level and in true alignment with adjacent walls. Where practical, piping from fixtures shall extend to nearest wall. (3) Brackets. Wall-hung fixtures shall be rigidly attached to walls by metal brackets or supports without any strain being transmitted to the piping connections. Flush tanks shall be securely fastened to toilets or to the wall with corrosive-resistant materials. (4) Tub supports. Bathtub rims at wall shall be supported on metal hangers or on end-grain wood blocking attached to the wall unless otherwise recommended by the manufacturer of the tub. (5) Fixture fittings. Faucets and diverters shall be installed so that the flow of hot water from the fittings corresponds to the left-hand side of the fitting. (6) Hydromassage bathtub—(i) Access panel. A door or panel of sufficient size must be installed to provide access to the pump for repair or replacement. (ii) Piping drainage. The circulation pump must be accessibly located above the crown weir of the trap. The pump drain line must be properly sloped to drain the volute after fixture use. (iii) Piping. Hydromassage bathtub circulation piping must be installed to be self-draining. (iv) Electrical. Wiring must comply with Articles 680.70, 680.71, and 680.72 of the National Electrical Code, NFPA No. 70-2005.

24 C.F.R. § 3280.608 Hangers and supports.

(a) Strains and stresses. Piping in a plumbing system shall be installed without undue strains and stresses, and provision shall be made for expansion, contraction, and structural settlement. (b) Piping supports. Piping must be secured at sufficiently close intervals to keep the pipe in alignment and carry the weight of the pipe and contents. Unless otherwise stated in the standards incorporated by reference for specific materials at § 3280.604(a), or unless specified by the pipe manufacturer, horizontal plastic drainage piping must be supported at intervals not to exceed 4 feet and horizontal plastic water piping must be supported at intervals not to exceed 3 feet. Vertical drainage and water piping must be supported at each story height. (c) Hangers and anchors. (1) Hangers and anchors shall be of sufficient strength to support their proportional share of the pipe alignments and prevent rattling. (2) Piping shall be securely attached to the structure by hangers, clamps, or brackets which provide protection against motion, vibration, road shock, or torque in the chassis. (3) Hangers and straps supporting plastic pipe shall not compress, distort, cut or abrade the piping and shall allow free movement of the pipe.

24 C.F.R. § 3280.609 Water distribution systems.

(a) Water supply—(1) Supply piping. Piping systems shall be sized to provide an adequate quantity of water to each plumbing fixture at a flow rate sufficient to keep the fixture in a clean and sanitary condition without any danger of backflow or siphonage. (See table in § 3280.609(f)(1)). The manufacturer shall include in his written installation instructions that the manufactured home has been designed for an inlet water pressure of 80 psi, and a statement that when the manufactured home is to be installed in areas where the water pressure exceeds 80 psi, a pressure reducing valve should be installed. (2) Hot water supply. Each manufactured home equipped with a kitchen sink, and bathtub and/or shower shall be provided with a hot water supply system including a listed water heater. (b) Water outlets and supply connections—(1) Water connection. Each manufactured home with a water distribution system shall be equipped with a 3/4 inch threaded inlet connection. This connection shall be tagged or marked “Fresh Water Connection” (or marked “Fresh Water Fill”). A matching cap or plug shall be provided to seal the water inlet when it is not in use, and shall be permanently attached to the manufactured home or water supply piping. When a master cold water shutoff full flow valve is not installed on the main feeder line in an accessible location, the manufacturer's installation instructions shall indicate that such a valve is to be installed in the water supply line adjacent to the home. When a manufactured home includes expandable rooms or is composed of two or more units, fittings or connectors designed for such purpose shall be provided to connect any water piping. When not connected, the water piping shall be protected by means of matching threaded caps or plugs. (2) Prohibited connections. (i) The installation of potable water supply piping or fixture or appliance connections shall be made in a manner to preclude the possibility of backflow. (ii) No part of the water system shall be connected to any drainage or vent piping. (3) Rim outlets. The outlets of faucets, spouts, and similar devices shall be spaced at least 1 inch above the flood level of the fixture. (4) Appliance connections. Water supplies connected to clothes washing or dishwashing machines shall be protected by an approved or listed fixed air gap provided within the appliance by the manufacturer. (5) Flushometer valves or manually operated flush valves. An approved or listed vacuum breaker shall be installed and maintained in the water supply line on the discharge side of a water closet flushometer valve or manually operated flush valve. Vacuum breakers shall have a minimum clearance of 6 inches above the flood level of the fixture to the critical level mark unless otherwise permitted in their approval. (6) Flush tanks. Water closet flush tanks shall be equipped with an approved or listed anti-siphon ball cock which shall be installed and maintained with its outlet or critical level mark not less than 1 inch above the full opening of the overflow pipe. (7) Hose bibbs. When provided, all exterior hose bibbs and laundry sink hose connections must be protected by a listed nonremovable backflow prevention device. This requirement is not applicable to hose connections provided for automatic washing machines with built-in backflow prevention or water heater drain valves. (8) Flushometer tanks. Flushometer tanks must be equipped with an approved air gap or vacuum breaker assembly that is located above the flood-level rim above the fixture. (c) Water heater safety devices—(1) Relief valves. (i) All water heaters shall be installed with approved and listed fully automatic valve or valves designed to provide temperature and pressure relief. (ii) Any temperature relief valve or combined pressure and temperature relief valve installed for this purpose shall have the temperature sensing element immersed in the hottest water within the upper 6 inches of the tank. It shall be set to start relieving at a pressure of 150 psi or the rated working pressure of the tank whichever is lower and at or below a water temperature of 210 °F. (iii) Relief valves must be provided with full-sized drains, with cross sectional areas equivalent to that of the relief valve outlet. The outlet of a pressure relief valve, temperature relief valve, or combination thereof, must not be directly connected to the drainage system. The discharge from the relief valve must be piped full size separately to the exterior of the manufactured home, not underneath the home, or to an indirect waste receptor located inside the manufactured home. Exterior relief drains shall be directed down and shall terminate between 6″ and 24″ above finished grade. Drain lines must be of a material listed for hot water distribution and must drain fully by gravity, must not be trapped, and must not have their outlets threaded, and the end of the drain must be visible for inspection. (iv) Relief valve piping designed to be located underneath the manufactured home is not required to be installed at the factory provided the manufacturer designs the system for site assembly and also provides all materials and components including piping, fittings, cement, supports, and instructions for proper site installation. (d) Materials—(1) Piping material. Water pipe shall be of standard weight brass, galvanized wrought iron, galvanized steel, Type K, L or M copper tubing, approved or listed plastic or other approved or listed material. (i) Plastic piping. All plastic water piping and fittings in manufactured homes must be listed for use with hot water. (ii) [Reserved] (2) Fittings. Appropriate fittings shall be used for all changes in size and where pipes are joined. The material and design of fittings shall conform to the type of piping used. Special consideration shall be given to prevent corrosion when dissimilar metals are joined. (i) Fittings for screw piping shall be standard weight galvanized iron for galvanized iron and steel pipe, and of brass for brass piping. They shall be installed where required for change in direction, reduction of size, or where pipes are joined together. (ii) Fittings for copper tubing shall be cast brass or drawn copper (sweat-soldered) or shall be approved or listed fittings for the purpose intended. (3) Prohibited material. Used piping materials shall not be permitted. Those pipe dopes, solder, fluxes, oils, solvents, chemicals, or other substances that are toxic, corrosive, or otherwise detrimental to the water system shall not be used. In addition, for those manufactured homes to be connected to a public water system, all water piping shall be lead-free (as defined in section 109(c)(2) of the Safe Drinking Water Act Amendments of 1986) with solders and flux containing not more than 0.2 percent lead and pipes and pipe fittings containing not more than 8.0 percent lead. (e) Installation of piping—(1) Minimum requirement. All piping equipment, appurtenances, and devices shall be installed in workmanlike manner and shall conform with the provisions and intent of this standard. (2) Screw pipe. Iron pipe-size brass or galvanized iron or steel pipe fittings shall be joined with approved or listed standard pipe threads fully engaged in the fittings. Pipe ends shall be reamed to the full bore of the pipe. Pipe-joint compound shall be insoluble in water, shall be nontoxic and shall be applied to male threads only. (3) Solder fittings. Joints in copper water tubes shall be made by the appropriate use of approved cast brass or wrought copper fittings, properly soldered together. The surface to be soldered shall be thoroughly cleaned bright mechanically. The joints shall be properly fluxed and made with a solder that contains no more than 0.2 percent lead. (4) Flared fittings. A flaring tool shall be used to shape the ends of flared tubing to match the flare of fittings. (5) Plastic pipe and fittings. Plastic pipe and fittings shall be joined by installation methods recommended by the manufacturer or in accordance with provisions of a listed standard. (f) Size of water supply piping—(1) Minimum size. The size of water supply piping and branch lines shall not be less than sizes shown in the following table: (2) Sizing procedure. Both hot and cold water piping systems shall be computed by the following method: (i) Size of branch. Start at the most remote outlet on any branch of the hot or cold water piping and progressively count towards the water service connection, computing the total number of fixtures supplied along each section of piping. Where branches are joined together, the number of fixtures on each branch shall be totalled so that no fixture is counted twice. Following down the left-hand column of the preceding table a corresponding number of fixtures will be found. The required pipe or tubing size is indicated in the other columns on the same line. (ii) A water heater, food waste disposal unit, evaporative cooler or ice maker shall not be counted as a water-using fixture when computing pipe sizes. (g) Line valves. Valves, when installed in the water supply distribution system (except those immediately controlling one fixture supply) and when fully opened, shall have a cross-sectional area of the smallest orifice or opening, through which the water flows, at least equal to the cross-sectional area of the nominal size of the pipe in which the valve is installed.

24 C.F.R. § 3280.610 Drainage systems.

(a) General. (1) Each fixture directly connected to the drainage system shall be installed with a water seal trap (§ 3280.606(a)). (2) The drainage system shall be designed to provide an adequate circulation of air in all piping with no danger of siphonage, aspiration, or forcing of trap seals under conditions of ordinary use. (b) Materials—(1) Pipe. Drainage piping must be standard weight galvanized steel, brass, copper tube DWV, listed Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved materials. (2) Fittings. Drainage fittings shall be recessed drainage pattern with smooth interior waterways of the same diameter as the piping and shall be of a material conforming to the type of piping used. Drainage fittings shall be designed to provide for a 1/4 inch per foot grade in horizontal piping. (i) Fittings for screw pipe shall be cast iron, malleable iron, brass, or listed plastic with standard pipe threads. (ii) Fittings for copper tubing shall be cast brass or wrought copper. (iii) Socket-type fittings for plastic piping shall comply with listed standards. (iv) Brass or bronze adaptor or wrought copper fittings shall be used to join copper tubing to threaded pipe. (c) Drain outlets. (1) General. Each manufactured home shall have only one drain outlet. (2) Clearance from drain outlet. The drain outlet shall be provided with a minimum clearance of 3 inches in any direction from all parts of the structure or appurtenances and with not less than 18 inches unrestricted clearance directly in front of the drain outlet. (3) Drain connector. The drain connector shall not be smaller than the piping to which it is connected and shall be equipped with a water-tight cap or plug matching the drain outlet. The cap or plug shall be permanently attached to the manufactured home or drain outlet. (4) Size Requirement. The drain outlet and drain connector shall not be less than 3 inches inside diameter. (5) Preassembly of drain lines. Section(s) of the drain system, designed to be located underneath the manufactured home or between stories of the manufactured home, are not required to be factory installed when the manufacturer designs the system for site assembly and also provides all materials and components, including piping, fittings, cement, supports, and instructions necessary for proper site installation. (d) Fixture connections. Drainage piping shall be provided with approved or listed inlet fittings for fixture connections, correctly located according to the size and type of fixture to be connected. (1) Water closet connection. The drain connection for each water closet shall be 3 inches minimum inside diameter and shall be fitted with an iron, brass, or listed plastic floor flange adaptor ring securely screwed, soldered or otherwise permanently attached to the drain piping, in an approved manner and securely fastened to the floor. (2) [Reserved] (e) Size of drainage piping. Fixture drains must be sized as follows: (1) Fixture drains serving a single lavatory must be a minimum of 1 1/4 inches in diameter. (2) Fixture drains serving two or three fixtures must be a minimum of 1 1/2 inches in diameter. (3) Fixture drains serving four or more fixtures that are individually vented must be a minimum of 2 inches in diameter. (4) Fixture drains for water closets must be a minimum of 3 inches in diameter. (f) Wet-vented drainage system. Plumbing fixture traps may connect into a wet-vented drainage system which shall be designed and installed to accommodate the passage of air and waste in the same pipe. (1) Horizontal piping. All parts of a wet-vented drainage system, including the connected fixture drains, shall be horizontal except for wet-vented vertical risers which shall terminate with a 1 1/2 inch minimum diameter continuous vent. Where required by structural design, wet-vented drain piping may be offset vertically when other vented fixture drains or relief vents are connected to the drain piping at or below the vertical offsets. (2) Size. A wet-vented drain pipe shall be 2 inches minimum diameter and at least one pipe size larger than the largest connected trap or fixture drain. Not more than three fixtures may connect to a 2-inch diameter wet-vented drain system. (3) Length of trap arm. Fixture traps shall be located within the distance given in § 3280.611(c)(5). Not more than one trap shall connect to a trap arm. (g) Offsets and branch fittings—(1) Changes in direction. Changes in direction of drainage piping shall be made by the appropriate use of approved or listed fittings, and shall be of the following angles: 11 1/4, 22 1/2, 45, 60, or 90 degrees; or other approved or listed fittings or combinations of fittings with equivalent radius or sweep. (2) Horizontal to vertical. Horizontal drainage lines, connecting with a vertical pipe shall enter through 45-degree “Y” branches, 60-degree “Y” branches, long-turn “TY” branches, sanitary “T” branches, or other approved or listed fittings or combination of fittings having equivalent sweep. Fittings having more than one branch at the same level shall not be used, unless the fitting is constructed so that the discharge from any one branch cannot readily enter any other branch. However, a double sanitary “T” may be used when the drain line is increased not less than two pipe sizes. (3) Horizontal to horizontal and vertical to horizontal. Horizontal drainage lines connecting with other horizontal drainage lines or vertical drainage lines connected with horizontal drainage lines shall enter through 45-degree “Y” branches, long-turn “TY” branches, or other approved or listed fittings or combination of fittings having equivalent sweep. (h) Grade of horizontal drainage piping. Except for fixture connections on the inlet side of the trap, horizontal drainage piping shall be run in practical alignment and have a uniform grade of not less than 1/4 inch per foot toward the manufactured home drain outlet. Where it is impractical, due to the structural features or arrangement of any manufactured home, to obtain a grade of 1/4 inch per foot, the pipe or piping may have a grade of not less than 1/8 inch per foot, when a full size cleanout is installed at the upper end.

24 C.F.R. § 3280.611 Vents and venting.

(a) General. Each plumbing fixture trap shall be protected against siphonage and back pressure, and air circulation shall be ensured throughout all parts of the drainage system by means of vents installed in accordance with the requirements of this section and as otherwise required by this standard. (b) Materials—(1) Pipe. Vent piping must be standard weight galvanized steel, brass, copper tube DWV, listed Scheduled 40 ABS plastic, listed Scheduled 40 PVC plastic, cast iron, or other listed or approved materials. (2) Fittings. Appropriate fittings shall be used for all changes in direction or size and where pipes are joined. The material and design of vent fittings shall conform to the type of piping used. (i) Fittings for screw pipe shall be cast iron, malleable iron, plastic, or brass, with standard pipe threads. (ii) Fittings for copper tubing shall be cast brass or wrought copper. (iii) Fittings for plastic piping shall be made to approved applicable standards. (iv) Brass adaptor fittings or wrought copper shall be used to join copper tubing to threaded pipe. (v) Listed rectangular tubing may be used for vent piping only providing it has an open cross section at least equal to the circular vent pipe required. Listed transition fittings shall be used. (c) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 1 1/2 inch minimum diameter vent or rectangular vent of venting cross section equivalent to or greater than the venting cross section of a 1 1/2 inch diameter vent, connected to the toilet drain by one of the following methods: (i) A 1 1/2 inch diameter (min.) individual vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in size through the roof; (ii) A 1 1/2-inch diameter (min.) continuous vent or equivalent, indirectly connected to the toilet drain piping within the distance allowed in paragraph (c)(5) of this section for 3 inch trap arms through a 2-inch wet vented drain that carries the waste of not more than one fixture. Sections of the wet vented drain that are 3 inches in diameter are permitted to carry the waste of an unlimited number of fixtures; or (iii) Two or more vented drains when at least one is wet-vented, or 2-inch diameter (minimum), and each drain is separately connected to the toilet drain. At least one of the drains shall connect within the distance allowed in § 3280.611(c)(5) for 3-inch trap arms. (2) Vent pipe areas. Each individually vented fixture with a 1 1/2 inch or smaller trap shall be provided with a vent pipe equivalent in area to a 1 1/4 inch nominal pipe size. The main vent, toilet vent and relief vent, and the continuous vent of wet-vented systems shall have an area equivalent to 1 1/2 inch nominal pipe size. (3) Common vent. When two fixture traps located within the distance allowed from their vent have their trap arms connected separately at the same level into an approved double fitting, an individual vent pipe may serve as a common vent without any increase in size. (4) Intersecting vents. Where two or more vent pipes are joined together, no increase in size shall be required; however, the largest vent pipe shall extend full size through the roof. (5) Distance of fixture trap from vent shall not exceed the values given in the following table: (d) Mechanical Vents. Where mechanical vents are used as a secondary vent system for plumbing fixtures that are protected by traps, the mechanical vents must comply with paragraphs (d)(1) or (2) of this section. (1) Spring-operated mechanical (anti-siphon) vents must comply with the following: (i) No more than two fixtures individually protected by the spring-operated mechanical vent may be drained by a common 1 1/2 inch diameter drain. (ii) The drain size for three or more fixtures individually protected by a spring-operated mechanical vent must be at least 2 inches in diameter. (iii) Spring-operated mechanical vents are restricted to venting fixtures with 1 1/2 inch traps. (iv) A spring-operated mechanical vent must be installed in a location that allows a free flow of air and is accessible for inspection, maintenance, and replacement. The sealing function must be at least 6 inches above the top of the trap arm. (v) Materials for the spring-operated mechanical vents must be as follows: (A) Cap and housing must be listed acrylonitrile-butadiene-styrene, DWV grade; (B) Stem must be DWV grade nylon or acetal; (C) Spring must be stainless steel wire, Type 302; and (D) Sealing disc must be either: (1) Neoprene, conforming to CISPI-HSN-85, Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4), and to ASTM C564-97, Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4); or (2) Other material, conforming to ASTM C920-02, Standard Specification for Elastomeric Joint Sealants (incorporated by reference, see § 3280.4), and to ASTM D4635-01, Standard Specification for Polyethylene Films Made from Low-Density Polyethylene for General Use and Packaging Applications (incorporated by reference, see § 3280.4). (2) Gravity-operated mechanical (air admittance valves) vents must comply with the following: (i) Where installed to vent any fixture, the drain system must have a minimum 1 1/2 inch diameter vent that terminates outside the manufactured home. (ii) Where gravity-operated mechanical vent devices terminate in the attic cavity, the following requirements must be met: (A) The attic cavity must be accessible; (B) The sealing device must be installed a minimum of 6 inches above the insulation materials; and (C) The attic must be vented in accordance with § 3280.504(c)(1)(i); (3) Mechanical vents must be installed in accordance with the vent manufacturer's instructions. (e) Grade and connections—(1) Horizontal vents. Each vent shall extend vertically from its fixture “T” or point of connection with the waste piping to a point not less than 6 inches above the extreme flood level of the fixture it is venting before offsetting horizontally or being connected with any other vent pipe. Vents for horizontal drains shall connect above the centerline of the drain piping ahead (downstream) of the trap. Where required by structural conditions, vent piping may offset below the rim of the fixture at the maximum angle or height possible. (f) Vent terminal. Vents must terminate through the roof or wall, or to a mechanical vent device in accordance with paragraph (d) of this section. (1) Roof extension. Each vent pipe must extend through its flashing and terminate vertically. Vents that extend through the roof must extend undiminished in size, not less than 2 inches above the roof. Vent openings must be at least 3 feet away from any motor-driven air intake that opens into any habitable area. (2) Wall extensions. Extensions through exterior walls must terminate downward, have a screen to prevent entrance of birds and rodents, and be located as follows: (i) Extensions must not be located beneath a door, window, or other opening; (ii) Extensions must be a minimum of 10 feet above the finished floor; (iii) Extensions must be located a minimum of 2 feet above any building opening that is within 10 feet horizontally of any extension; and (iv) Extensions must not terminate under an overhang with soffit vents. (3) Flashing. The opening around each vent pipe shall be made watertight by an adequate flashing or flashing material. (g) Vent caps. Vent caps, if provided, shall be of the removable type (without removing the flashing from the roof). When vent caps are used for roof space ventilation and the caps are identical to vent caps used for the plumbing system, plumbing system caps shall be identified with permanent markings.

24 C.F.R. § 3280.612 Tests and inspection.

(a) Water system. All water piping in the water distribution system must be subjected to a pressure test. The test must be made by subjecting the system to air or water at 80 psi + or − 5 psi for 15 minutes without loss of pressure. The water used for the test must be obtained from a potable water source. (b) Drainage and vent system and plumbing fixtures. The waste and vent system shall be tested by one of the three following alternate methods for evidence or indication of leakage: (1) Water test. Before plumbing fixtures are connected, all of the openings into the piping shall be plugged and the entire piping system subjected to a static water test for 15 minutes by filling it with water to the top of the highest vent opening. There shall be no evidence of leakage. (2) Air test. After all fixtures have been installed, the traps filled with water, and the remaining openings securely plugged, the entire system shall be subjected to a 2-inch (manometer) water column air pressure test. If the system loses pressure, leaks may be located with smoke pumped into the system, or with soap suds spread on the exterior of the piping (Bubble test). (3) Flood level test. The manufactured home shall be in a level position, all fixtures shall be connected, and the entire system shall be filled with water to the rim of the water closet bowl. (Tub and shower drains shall be plugged). After all trapped air has been released, the test shall be sustained for not less than 15 minutes without evidence of leaks. Then the system shall be unplugged and emptied. The waste piping above the level of the water closet bowl shall then be tested and show no indication of leakage when the high fixtures are filled with water and emptied simultaneously to obtain the maximum possible flow in the drain piping. (c) Fixture test. The plumbing fixtures and connections shall be subjected to a flow test by filling them with water and checking for leaks and retarded flow while they are being emptied. (d) Shower compartments. Shower compartments and receptors shall be tested for leaks prior to being covered by finish material. Each pan shall be filled with water to the top of the dam for not less than 15 minutes without evidence of leakage.

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