Water Supply and Distribution

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

• CPC § 2025 High relevance — show source text

  An acceptable air supply for combustion and ventilation is necessary for the proper operation of fuel-burning appliances. A shortage of combustion air can result in incomplete combustion and the production of poisonous gases, such as carbon monoxide or appliance overheating. Ventilation air provides cooling for the appliance casing and internal controls. Inadequate ventilation of the space in which an appliance is installed can result in increased surrounding temperatures that stress the appliance itself or other appliances in the vicinity.

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  FORMAT OF THE UNIFORM PLUMBING CODE

  Chapter 6 Water Supply and Distribution.

  Chapter 6 regulates the design, material, and installation of water supply and distribution systems, including residential fire sprinklers. The water supply and distribution system is designed to achieve the correct water pressure and flow rates and avoid cross-connections. For fixtures to perform properly, an acceptable supply of potable water is essential to their operation and use. Cross-connections and backflow are ranked as the highest priority because of the long history of recognized health risks posed by cross-connections, outbreaks, or cases of waterborne disease. Piping materials and components are evaluated for their possible effect on the potable water with which they are in contact. The intent is to control the potential adverse health effects produced by indirect additives, products, and materials that come in contact with potable water. When selecting materials for water supply and distribution systems, consider water pressure, water temperature, compatibility with the water supply, durability, support, and sustainability.

  In addition, this chapter regulates the design, location, materials, and installation of multipurpose and stand-alone sprinkler systems that do not include the use of antifreeze. Where systems are installed as a portion of the water distribution system under the requirements of this chapter and are not provided with a fire department connection, backflow protection for the water supply system is not required.

  Chapter 7 Sanitary Drainage.

  This chapter regulates the design and installation of sanitary drainage systems to ensure they will work as intended. Drainage piping should not be oversized nor undersized, and constructed of approved materials to guard against fouling, deposit of solids, clogging, and with cleanouts so arranged that the pipes may be readily cleaned. The purpose of the sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment to an approved point of disposal, such as a public sanitary system or private sewage disposal system.

  The basics of a sanitary drainage system include public and private sewage disposal; selection of materials; installation of the building drain and sewer; joining methods for pipe and fittings; drainage fixture units for sizing the drainage system; sumps and ejectors; vent sizing and length of vents; and testing.

  Chapter 8 Indirect Wastes.

  Chapter 8 regulates indirect waste connections that are required for plumbing fixtures and plumbing appliances dealing with food preparation, dishwashing, potable liquids, and similar equipment. An indirect connection prevents sewage from backing up into a fixture or appliance, thus providing protection against potential health hazards. The waste pipe discharges through an air gap or air break into a waste receptor or standpipe. The protection in the form of an air gap is necessary when the contamination is a potential health hazard or cross connection with the potable water system. Where there is no possibility of contaminating the potable water (nonpotable discharge), the indirect waste pipe may connect in the form of an air break.

• CPC § 2025 High relevance — show source text

  The safety requirements provide protection for piping, material, and structures, with provisions for installation practices, removing stress and strain of the pipe, sleeving, and hanger support. The building’s structural stability is protected by the regulations for cutting and notching of structural members.

  Chapter 4 Plumbing Fixtures and Fixture Fittings.

  This chapter regulates the minimum number of plumbing fixtures of a specific type and quality for each building. The fixtures must be properly installed to be usable by the individuals occupying the building. The quality and design of every fixture must conform to the applicable referenced standard. Compliance with this chapter will result in a building or structure having acceptable plumbing fixtures for the sanitary, hygienic, cleaning, washing, and food preparation needs of the occupants. In addition to ensuring resilient fixtures, the chapter also takes into consideration gender-neutral facilities and contains provisions for privacy compartments.

  Chapter 5 Water Heaters.

  Chapter 5 regulates the design, approval, installation, and safety devices of fuel burning and other types of water heaters with the combustion air requirements for ventilation and dilution of flue gases for appliances installed in buildings. This chapter does not apply to direct-vent appliances. In addition, this chapter regulates the design, construction, installation, and maintenance of chimneys, vents, and their connections to fuel-burning appliances. Methods to supply combustion air may be supplied from an indoor air supply, outdoor air supply, a combination of indoor and outdoor air supply, mechanical air supply, or an engineered system. Combustion air provisions are based on the number of openings and the total opening size required based on the total energy input rating of the appliance. An acceptable air supply for combustion and ventilation is necessary for the proper operation of fuel-burning appliances. A shortage of combustion air can result in incomplete combustion and the production of poisonous gases, such as carbon monoxide or appliance overheating. Ventilation air provides cooling for the appliance casing and internal controls. Inadequate ventilation of the space in which an appliance is installed can result in increased surrounding temperatures that stress the appliance itself or other appliances in the vicinity.

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  FORMAT OF THE UNIFORM PLUMBING CODE

  Chapter 6 Water Supply and Distribution.

  Chapter 6 regulates the design, material, and installation of water supply and distribution systems, including residential fire sprinklers. The water supply and distribution system is designed to achieve the correct water pressure and flow rates and avoid cross-connections. For fixtures to perform properly, an acceptable supply of potable water is essential to their operation and use. Cross-connections and backflow are ranked as the highest priority because of the long history of recognized health risks posed by cross-connections, outbreaks, or cases of waterborne disease. Piping materials and components are evaluated for their possible effect on the potable water with which they are in contact. The intent is to control the potential adverse health effects produced by indirect additives, products, and materials that come in contact with potable water. When selecting materials for water supply and distribution systems, consider water pressure, water temperature, compatibility with the water supply, durability, support, and sustainability.

• CPC § 12.3 High relevance — show source text

  12.3_|||||||||||||||||||||X|||| |Table 610.3||||X|X|||||||||||||||||||| |610.5||||X|X|||||||||||||||||||| |612.0|||X|||||||||||||||||||||| |612.1|||X|||||||||||||||||||||| |613.0||||||||||X||X|X|X|X|||||||||| |Table 613.1||||||||||X||X|X|X|X|||||||||| |614.0||||||||||X||X|X|X|X|||||||||| |615.0||||||||||X|X|X|X|X|X|||||||||| |616.0||||||||||X|||||||||||||||

  This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

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  CHAPTER 6

  WATER SUPPLY AND DISTRIBUTION

  601.0 General.

  601.1 Applicability. This chapter shall govern the materials, design, and installation of water supply systems, including methods and devices used for backflow prevention. 601.2 Water Supply and Flushing. Each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, so arranged as to flush and keep it in a clean and sanitary condition without danger of backflow or cross-connection. Water closets and urinals shall be flushed using an approved flush tank or flushometer valve.

  Exceptions:

  (1) Listed fixtures that do not require water for their operation and are not connected to the water supply.

  (2) Where not deemed necessary for safety and sanitation by the Authority Having Jurisdiction. (3) [HCD 1 & HCD 2] For limited-density owner-built rural dwellings, potable water shall be available to the dwelling site, although such water need not be pressur- ized. Where water is not piped from a well, spring, cistern or other source, there shall be a minimum reserve of 50 gallons (189 L) of potable water available. Where water delivery is pressurized, piping shall be installed in accor- dance with the provisions of this chapter. (4) [HCD 1, HCD 2 & DWR] For all residential occupan- cies, alternate water sources may be allowed as speci- fied in Chapter 15 of this code in addition to potable

  water.

  (5) [BSC-CG & DWR] For non-residential occupancies, alternate water sources may be allowed as specified in Chapter 15 of this code.

• CPC § 309.0 High relevance — show source text

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  IS 33

  Uniform Plumbing Code References for Ductile Iron and PVC Pressure Building Supply and Exterior Cold-Water Piping

  The following sections of the 2024 Uniform Plumbing Code apply to ductile iron and PVC pressure building supply and exterior cold-water piping.

  Chapter 3 General Regulations

  309.0 Workmanship

  312.0 Protection of Piping, Materials, and Struc tures

  313.0 Hangers, Supports, and Anchors

  314.0 Trenching, Excavation, and Backfill

  Chapter 6 Water Supply and Distribution

  604.0 Materials (water piping)

  Table 604.1 Materials for Building Supply and Water Distribution Piping and Fittings

  605.4 Ductile Iron Pipe and Joints

  605.12 PVC Plastic Pipe and Joints

  605.16.2 Plastic Pipe to Other Materials

  609.0 Installation, Testing, Unions, and Location

  Abbreviations

  IAPMO International Association of Plumbing and Mechanical Officials

  UPC Uniform Plumbing Code published by IAPMO

  AWWA American Water Works Association

  CSA Canadian Standards Association

  Applicable Standards.

  ASME B16.4 Gray Iron Threaded Fittings Classes 125 and 250

  ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120

  ASTM D2241 Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

  ASTM D2466 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40

  ASTM D2467 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80

  ASTM F1970 Special Engineered Fittings, Appurtenances or Valves for use in Poly (Vinyl Chloride) (PVC) or Chlorinated Poly (Vinyl Chloride) (CPVC) Systems

  AWWA C110 Ductile Iron and Gray-Iron Fittings

  AWWA C111 Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings

  AWWA C151 Ductile-Iron Pipe, Centrifugally Cast

  AWWA C153 Ductile-Iron Compact Fitting

  AWWA C900 Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 in. through 12 in. (100 mm through 300 mm)

  AWWA C904 Crosslinked Polyethylene (PEX) Pressure Tubing, ½ in. through 3 In. (13 mm through 76 mm), for Water Service

  AWWA C907 Injection-Molded Polyvinyl Chloride (PVC) Pressure Fittings, 4 In, through 12 in (100 mm through 300 mm) for Water, Wastewater and Reclaimed Water Service

  IAPMO/

  ANSI UPC-1 Uniform Plumbing Code

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• CPC § 202.2 High relevance — show source text

  R 202.2 Sizing Water Supply and Distribution Sys- tems. Water distribution systems shall be sized in accordance with Section 610.0. Water supply piping, joints, and connections shall be installed in accordance with Chapter 6. R 202.3 Pressure. Each tiny house water distribution system shall be so designed and maintained at not less than 15 pounds force per square inch (psi) (103 kPa) at each fixture inlet in accordance with Section 608.1. Water pressure exceeding 80 psi (552 kPa), shall be limited in accordance with Section 608.2.

  R 203.0 Tiny House Drain, Waste, and Vent (DWV) System. R 203.1 General. Sanitary drain, waste, and vent (DWV) systems shall be installed in accordance with Chapter 7 and Chapter 9. The DWV system shall connect to the public sanitary waste system. Private sewage disposal systems shall be permitted where approved by the Authority Having Jurisdiction. See Appendix H for private sewage disposal system general guidelines.

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  CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

  APPENDIX S - ONSITE STORMWATER TREATMENT SYSTEMS

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	** SS**	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
  Adopt Entire Chapter				X
  Adopt Entire Chapter as amended (amended sections listed below)
  Adopt only those sections that are listed below
  Chapter/Section

  This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

  2025 CALIFORNIA PLUMBING CODE 547

• CPC § 610.3 High relevance — show source text

  No water filter, water softener, backflow prevention device, or similar device regulated by this code shall be installed in a potable water supply piping where the installation of such device produces an excessive pressure drop in such water supply piping. In the absence of specific pressure drop information, the diameter of the inlet or outlet of such device or its connecting piping shall be not less than the diameter of such water distribution piping to the fixtures served by the device.

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  WATER SUPPLY AND DISTRIBUTION

  Such devices shall be of a type approved by the Authority Having Jurisdiction and shall be tested for flow rating and pressure loss by an approved laboratory or recognized testing agency to standards consistent with the intent of this chapter. 610.3 Quantity of Water. The quantity of water required to be supplied to every plumbing fixture shall be represented by fixture units, as shown in Table 610.3. Equivalent fixture values shown in Table 610.3 include both hot and cold water demand.

  610.4 Sizing Water Supply and Distribution Systems. Systems within the range of Table 610.4 shall be permitted to be sized from that table or by the method in accordance with Section 610.5.

  Listed parallel water distribution systems shall be installed in accordance with their listing, but at no time shall a portion of the system exceed the maximum velocities allowed by the code. 610.5 Sizing per Appendices A, C, and M . Except as provided in Section 610.4, the size of each water piping system shall be determined in accordance with the procedure set forth in Appendix A. For alternative methods of sizing water supply systems, see Appendix C or Appendix M . 610.6 Friction and Pressure Loss. Except where the type of pipe used and the water characteristics are such that no decrease in capacity due to the length of service (age of system) is expected, friction-loss data shall be obtained from the “Fairly Rough” or “Rough” charts in Appendix A of this code. Friction or pressure losses in a water meter, valve, and fittings shall be obtained from the same sources. Pressure losses through water-treating equipment, backflow prevention devices, or other flow-restricting devices shall be computed in accordance with Section 610.2. 610.7 Conditions for Using Table 610.4. On a proposed water piping installation sized using Table 610.4, the following conditions shall be determined:

  (1) Total number of fixture units as determined from Table 610.3, Equivalent Fixture Units, for the fixtures to be installed.

  (2) Developed length of supply pipe from meter to the most remote outlet.

  (3) Difference in elevation between the meter or other source of supply and the highest fixture or outlet.

  (4) Pressure in the street main or another source of supply at the locality where the installation is to be made.

  (5) In localities where there is a fluctuation of pressure in the main throughout the day, the water piping system shall be designed on the basis of the minimum pressure available. 610.8 Size of Meter and Building Supply Pipe Using Table 610.4. The size of the meter and the building supply pipe shall be determined as follows:

  (1) Determine the available pressure at the water meter or other source of supply.

• CPC § 4.1 High relevance — show source text

  • 100°F
    (16°C-38°C)|1 h|6 h|2 h|12 h|6 h|24 h| |40°F-60°F
    (4°C-16°C)|2 h|12 h|4 h|24 h|12 h|48 h| |10°F- 40°F
    (-12°C+4°C)|8 h|48 h|16 h|96 h|48 h|8 days| |*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|

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  IS 33

  FIGURE 1

  LOCATION OF THRUST BLOCKS (STANDARD AND METRIC COMBINED) A COMPARISON OF THRUST-BLOCK AREAS (See Section 4.1)

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  IS 33

  FIGURE 2

  THRUST BLOCK BEARING AREA (See Section 5.2.2)

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  IS 33

  Uniform Plumbing Code References for Ductile Iron and PVC Pressure Building Supply and Exterior Cold-Water Piping

  The following sections of the 2024 Uniform Plumbing Code apply to ductile iron and PVC pressure building supply and exterior cold-water piping.

  Chapter 3 General Regulations

  309.0 Workmanship

  312.0 Protection of Piping, Materials, and Struc tures

  313.0 Hangers, Supports, and Anchors

  314.0 Trenching, Excavation, and Backfill

  Chapter 6 Water Supply and Distribution

  604.0 Materials (water piping)

  Table 604.1 Materials for Building Supply and Water Distribution Piping and Fittings

  605.4 Ductile Iron Pipe and Joints

  605.12 PVC Plastic Pipe and Joints

  605.16.2 Plastic Pipe to Other Materials

  609.0 Installation, Testing, Unions, and Location

  Abbreviations

  IAPMO International Association of Plumbing and Mechanical Officials

  UPC Uniform Plumbing Code published by IAPMO

  AWWA American Water Works Association

  CSA Canadian Standards Association

  Applicable Standards.

  ASME B16.4 Gray Iron Threaded Fittings Classes 125 and 250

  ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120

  ASTM D2241 Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

• CPC § 201.6 Medium relevance — show source text

  R 201.6 Water Closet. Water closets shall be in accordance

  with Section 411.0.

  R 201.7 Lavatories. Lavatories shall be in accordance with

  Section 407.0.

  R 202.0 Tiny House Water Supply System. R 202.1 Water Service Outlet. Each tiny house shall be provided with a water service outlet delivering potable water. The water service outlet riser shall be not less than ¾ of an inch (20 mm) nominal pipe size. R 202.2 Sizing Water Supply and Distribution Sys- tems. Water distribution systems shall be sized in accordance with Section 610.0. Water supply piping, joints, and connections shall be installed in accordance with Chapter 6. R 202.3 Pressure. Each tiny house water distribution system shall be so designed and maintained at not less than 15 pounds force per square inch (psi) (103 kPa) at each fixture inlet in accordance with Section 608.1. Water pressure exceeding 80 psi (552 kPa), shall be limited in accordance with Section 608.2.

  R 203.0 Tiny House Drain, Waste, and Vent (DWV) System. R 203.1 General. Sanitary drain, waste, and vent (DWV) systems shall be installed in accordance with Chapter 7 and Chapter 9. The DWV system shall connect to the public sanitary waste system. Private sewage disposal systems shall be permitted where approved by the Authority Having Jurisdiction. See Appendix H for private sewage disposal system general guidelines.

  2025 CALIFORNIA PLUMBING CODE 545

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  CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

  APPENDIX S - ONSITE STORMWATER TREATMENT SYSTEMS

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

• CPC § 103.3 Medium relevance — show source text

  R 103.3 Water Heaters. Water heaters shall be installed in accordance with Chapter 5 and the manufacturer’s recommendations and instructions.

  R 103.4 Potable Water Sources. Where a public water supply system is available, it shall be used. Private or alternate water sources shall comply with the potable water standards of the state, and local health authority. R 103.5 Water Supply to Fixtures. Each plumbing fixture shall be provided with an adequate supply of potable water in accordance with Chapter 6.

  R 103.6 Protection of Potable Water. The potable water supply shall be protected from pollution and contamination in accordance with Section 602.0 and Section 603.0. Backflow prevention shall be in accordance with Table 603.2.

  R 103.7 Water-Treatment Equipment. Where installed, water-treatment equipment shall comply with the requirements of Section 611.0.

  R 103.8 Testing. Installations of water supply, drainage, and venting systems shall be tested and inspected in accordance with the requirements of this code.

  R 201.0 Tiny House Fixtures.

  R 201.1 Fixtures. Plumbing fixtures shall comply with the requirements of Chapter 4.

  R 201.2 Kitchen. Each tiny house shall be provided with a kitchen sink.

  R 201.3 Bathroom. Each tiny house shall be provided with not less than one water closet, one lavatory, and one bath, shower or combination bath/shower.

  R 201.4 Bathtubs and Whirlpool Bathtubs. Where installed, bathtubs and whirlpool bathtubs shall be in accordance with Section 409.0.

  R 201.5 Showers Compartments. Where installed, shower compartment enclosures shall be not less than 30 inches (762 mm) wide by 30 inches (762 mm) long.

  R 201.6 Water Closet. Water closets shall be in accordance

  with Section 411.0.

  R 201.7 Lavatories. Lavatories shall be in accordance with

  Section 407.0.

  R 202.0 Tiny House Water Supply System. R 202.1 Water Service Outlet. Each tiny house shall be provided with a water service outlet delivering potable water. The water service outlet riser shall be not less than ¾ of an inch (20 mm) nominal pipe size. R 202.2 Sizing Water Supply and Distribution Sys- tems. Water distribution systems shall be sized in accordance with Section 610.0. Water supply piping, joints, and connections shall be installed in accordance with Chapter 6. R 202.3 Pressure. Each tiny house water distribution system shall be so designed and maintained at not less than 15 pounds force per square inch (psi) (103 kPa) at each fixture inlet in accordance with Section 608.1. Water pressure exceeding 80 psi (552 kPa), shall be limited in accordance with Section 608.2.

  R 203.0 Tiny House Drain, Waste, and Vent (DWV) System. R 203.1 General. Sanitary drain, waste, and vent (DWV) systems shall be installed in accordance with Chapter 7 and Chapter 9. The DWV system shall connect to the public sanitary waste system. Private sewage disposal systems shall be permitted where approved by the Authority Having Jurisdiction. See Appendix H for private sewage disposal system general guidelines.

• CPC § 31-2022 Medium relevance — show source text

  2025 CALIFORNIA PLUMBING CODE 453

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  "The information contained in this appendix is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this appendix may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard."

  The following IAPMO Installation Standard is included here for the convenience of the users of the Uniform Plumbing Code. It is not considered as a part of the Uniform Plumbing Code unless formally adopted as such. This Installation Standard is an independent, stand-alone document published by the International Association of Plumbing and Mechanical Officials and is printed herein by the expressed written permission of IAPMO.

  INSTALLATION STANDARD FOR PEX TUBING SYSTEMS

  FOR HOT- AND COLD-WATER DISTRIBUTION

  IAPMO IS 31-2022

  The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

  1 Scope

  1.1 General

  1.1.1 This Standard specifies requirements for the installation of SDR 9 CTS crosslinked polyethylene (PEX) tubing and fittings, including cold-expansion, crimp, press, and mechanical compression fittings, intended for hot- and cold-water distribution systems within buildings.

  1.1.2 This Standards applies to

  (a) SDR 9 CTS PEX tubing complying with ASTM F876 and pressure-rated in accordance with PPI TR-3; and (b) PEX fitting systems complying with (i) ASTM F877, for mechanical compression fittings and metal or plastic insert fittings with stainless steel press sleeves; (ii) ASTM F1807 or ASTM F2159, for metal or plastic insert fittings with copper crimp rings; (iii) ASTM F1960, for cold expansion fittings with PEX reinforced rings; or (iv) ASTM F2080, for cold expansion fittings with metal compression sleeves. 1.2 Terminology

  In this Standard,

  (a) “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy to comply with the Standard; (b) “should” is used to express a recommendation, but not a requirement; (c) “may” is used to express an option or something permissible within the scope of the Standard; and (d) “can” is used to express a possibility or a capability. Notes accompanying sections of the Standard do not specify requirements or alternative requirements; their purpose is to separate explanatory or informa

  tive material from the text. Notes to tables and figures are considered part of the table or figure and can be written as requirements.

  1.3 Units of Measurement

  SI units are the primary units of record in global commerce. In this Standard, the inch/pound units are shown in parentheses. The values stated in each measurement system are equivalent in application, but each unit system is to be used independently. All references to gallons are to U.S. gallons.

  2 Reference Publications

• CPC § 602.0 Medium relevance — show source text

  602.0 Unlawful Connections.

  602.1 Prohibited Installation. No installation of potable water supply piping, or part thereof, shall be made in such a manner that it will be possible for used, unclean, polluted, or contaminated water, mixtures, or substances to enter a portion of such piping from a tank, receptor, equipment, or plumbing fixture by reason of backsiphonage, suction, or other cause, either during normal use and operation thereof, or where such tank, receptor, equipment, or plumbing fixture is flooded or subject to pressure exceeding the operating pressure in the hot or cold water piping. 602.2 Cross-Contamination. No person shall make a connection or allow one to exist between pipes or conduits carrying domestic water supplied by a public or private building supply system, and pipes, conduits, or fixtures containing or carrying water from any other source or containing or carrying water that has been used for any purpose whatsoever, or piping carrying chemicals, liquids, gases, or substances whatsoever, unless there is provided a backflow prevention device approved for the potential hazard and maintained in accordance with this code. Each point of use shall be separately protected where potential cross-contamination of individual units exists.

  602.3 Backflow Prevention. No plumbing fixture, device, or construction shall be installed or maintained, or shall be connected to a domestic water supply, where such installation or connection provides a possibility of polluting such water supply or cross-connection between a distributing system of water for drinking and domestic purposes and water that becomes contaminated by such plumbing fixture, device, or construction unless there is provided a backflow prevention device approved for the potential hazard.

  602.4 Approval by Authority. No water piping supplied by a private water supply system shall be connected to any other source of supply without the approval of the Authority Having Jurisdiction, Health Department, or other department having jurisdiction.

  603.0 Cross-Connection Control.

  603.1 General. Cross-connection control shall be provided in accordance with the provisions of this chapter.

  No person shall install a water-operated equipment or mechanism, or use a water-treating chemical or substance, where it is found that such equipment, mechanism, chemical, or substance causes pollution or contamination of the domestic water supply. Such equipment or mechanism shall be permitted where equipped with an approved backflow prevention device or assembly.

  603.2 Approval of Devices or Assemblies. Before a device or an assembly is installed for the prevention of backflow, it shall have first been approved by the Authority Having Jurisdiction. Devices or assemblies shall be tested in accordance with recognized standards or other standards acceptable to the Authority Having Jurisdiction. Backflow prevention devices and assemblies shall comply with Table 603.2, except for specific applications and provisions as stated in Section 603.5.1 through Section 603.5.22.

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  WATER SUPPLY AND DISTRIBUTION

• CPC § 422.1 Medium relevance — show source text

  6 Assembly [Public Use (See Table 422.1)]. 7 Where sizing flushometer systems, see Section 610.10. 8 Reduced fixture unit loading for additional hose bibbs is to be used where sizing total building demand and for pipe sizing where more than one hose bibb is supplied by a segment of water distribution pipe. The fixture branch to each hose bibb shall be sized on the basis of 2.5 fixture units. 9 For water supply fixture unit values related to lots within mobilehome parks in all parts of the State of California, see California Code of Regulations, Title 25, Division 1, Chapter 2, Article 5, Section 1278. For water supply fixture unit values related to lots within special occupancy parks in all parts of the State of California, see California Code of Regulations, Title 25, Division 1, Chapter 2.2, Article 5, Section 2278.

  158 2025 CALIFORNIA PLUMBING CODE

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  WATER SUPPLY AND DISTRIBUTION

  Col1	Col2	TABLE 610.4 FIXTURE UNIT TABLE FOR DETERMINING WATER PIPE AND METER SIZES	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Col11	Col12	Col13	Col14	Col15	Col16	Col17
  METER AND STREET SERVICE (inches)	BUILDING SUPPLY AND BRANCHES (inches)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)	MAXIMUM ALLOWABLE LENGTH (feet)
  METER AND STREET SERVICE (inches)	BUILDING SUPPLY AND BRANCHES (inches)	40	60	80	100	150	200	250	300	400	500	600	700	800	900	1000
  PRESSURE RANGE – 30 to 45 psi1	PRESSURE RANGE – 30 to 45 psi1	**PRESSURE RANGE