CPC · California Plumbing Code

What separation is required between nonpotable and potable piping?

Short answer for a homeowner: the California Plumbing Code allows nonpotable and potable pipes in the same trench only if they’re separated — usually by at least 12 inches vertically and horizontally (potable pipe above nonpotable). If the pipe materials aren’t approved for in‑building use, the horizontal separation must be much larger (60 inches). See **§ 1601.10** and consult **§ 609.2** or your local inspector for the building‑sewer specifics.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Plumbing Code requires that treated nonpotable water piping be separated from potable water piping when run in the same trench, and refers underground rainwater catchment service piping separation to § 609.2. For treated nonpotable water run in the same trench as potable water, the code sets a minimum vertical and horizontal separation of 12 inches (305 mm) where both pipe materials are approved for use within a building; where horizontal piping materials do not meet that requirement the horizontal separation must be increased to 60 inches (1524 mm) and the potable water piping must be installed above the nonpotable piping. See § 1601.10 for the rainwater/text reference to § 609.2.

The single most important rule: when treated nonpotable and potable pipes share a trench, keep potable above nonpotable and maintain at least 12 in. vertical and horizontal separation (or the larger horizontal spacing required where materials don’t qualify).

Requirements in detail

Key defined terms (first use bolded)

  • Treated nonpotable water — nonpotable water that has been treated for a specific nonpotable use (e.g., rainwater catchment, on‑site treated gray water, recycled water), as addressed in Chapters 15–16.
  • Potable water piping — piping conveying water suitable for drinking and domestic purposes.

Trench separation rule (applies when pipes are in the same trench)

Decision factor Required separation / action Code reference (where stated)
Both pipe materials are approved for in‑building use 12 inches (305 mm) minimum vertical and horizontal separation; potable pipe must be installed above nonpotable pipe § 1601.10
Horizontal piping materials do NOT meet the approved‑materials requirement Increase horizontal separation to 60 inches (1524 mm); potable pipe still above nonpotable § 1601.10
Underground rainwater catchment service piping vs building sewer Must be separated in accordance with § 609.2 (see § 1601.10 reference) § 1601.10 references § 609.2

Notes:

  • The separation requirements above are stated directly in § 1601.10 (nonpotable rainwater catchment) and analogous separation rules appear elsewhere in the Alternate Water Sources chapter (see Related provisions).

What "where both pipe materials are approved for use within a building" means

  • The 12‑inch (305 mm) reduced spacing applies only when the materials for both pipes meet the code’s materials and listing requirements for use inside buildings (i.e., they are compatible and approved for potable or nonpotable distribution as required). If materials are not approved or compatible, the code forces the larger spacing (60 in.).

Exceptions & special cases

  • Where the CPC (other chapters) addresses specific nonpotable types, the horizontal increase may differ: for example, some reclaimed/recycled water provisions reference a 48‑inch (1220 mm) increased horizontal spacing in their chapter text (see § 1505.12 for recycled water pipe separation language). Always check the chapter that governs the exact nonpotable source.
  • The CPC’s nonpotable rainwater catchment chapter defers separation from the building sewer to § 609.2 (text for § 609.2 was not present in the retrieved file excerpts; see note below). Do not assume the details of § 609.2 without consulting that section or your AHJ.

(Important retrieval note: the uploaded CPC excerpts include the separation requirements in § 1601.10, and multiple sections referencing § 609.2, but the full text of § 609.2 itself was not present in the search results I retrieved. I therefore cannot quote or paraphrase § 609.2 directly from the uploaded files — you should consult § 609.2 in your copy of the CPC or the Authority Having Jurisdiction for the building‑sewer separation specifics.)

Common mistakes

  • Assuming the same increased horizontal separation applies to every nonpotable source — some chapters say 60 in., some use 48 in.; always check the chapter for the specific nonpotable source (e.g., on‑site gray water, recycled water, rainwater).
  • Forgetting to install potable piping at a higher elevation than nonpotable piping when they are in the same trench. The code explicitly requires potable piping to be installed above the nonpotable line.
  • Overlooking the phrase “where both pipe materials are approved for use within a building” — if either pipe material is NOT approved for in‑building use, you must use the larger horizontal separation.
  • Using the reduced 12‑inch horizontal spacing without documented AHJ approval or without confirming materials are listed/approved for in‑building use.

Worked example — concrete scenario

Scenario: A contractor is running a buried potable copper main and a treated rainwater supply (PVC) in the same trench to serve irrigation. Both pipe materials are listed/approved for use within the building.

  • Required vertical and horizontal separation: 12 inches (305 mm). Install potable copper above the treated rainwater PVC and maintain at least 12 in. horizontally and vertically between the outside surfaces of the two pipes. Rationale: meets the “both pipe materials approved” condition in § 1601.10.

If the treated rainwater piping were an unlisted material (or the potable pipe material were noncompliant), the horizontal separation would have to be increased to 60 inches (1524 mm) per § 1601.10. In that case the designer would either change materials to approved ones (to use the 12 in. spacing) or provide the wider trench spacing.

Related provisions

  • § 1601.10 — Separation requirements for underground rainwater catchment and treated nonpotable piping (primary source for the 12 in. / 60 in. rule).
  • § 1502.4 — Separation requirements for alternate water source piping (mirrors 12 in. / 60 in. language for treated nonpotable water).
  • § 1505.12 — Pipe separation in trenches for reclaimed (recycled) water; includes 12 in. minimum and increases where materials don’t meet the requirement (chapter uses 48 in. for the increased horizontal separation in that particular chapter).
  • § 1506.10.4 — On‑site treated nonpotable (gray) water near underground potable water pipe: repeats 12 in. and 60 in. options for certain gray water systems.
  • § 609.2 — Referenced by § 1601.10 for separation from the building sewer (text not included in the retrieved excerpts; consult the CPC or AHJ for full language).

Code references

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

  • CPC § 1601.10 High relevance — show source text

    1601.10 Separation Requirements. Underground rainwater catchment service piping shall be separated from the building sewer in accordance with Section 609.2. Treated nonpotable water pipes shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where horizontal piping materials do not meet this requirement, the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the treated nonpotable water piping. 1601.11 Abandonment. Rainwater catchment systems that are no longer in use, or fail to be maintained in accordance with Section 1601.5, shall be abandoned. Abandonment shall comply with Section 1601.11.1 and Section 1601.11.2.

    1601.11.1 General. An abandoned system or part thereof covered under the scope of this chapter shall be disconnected from remaining systems, drained, plugged, and capped in an approved manner. 1601.11.2 Underground Tank. An underground water storage tank that has been abandoned or otherwise discontinued from use in a system covered under the scope of this chapter shall be completely drained and filled with earth, sand, gravel, concrete, or other approved material or removed in a manner satisfactory to the Authority Having Jurisdiction. 1601.12 Sizing. Unless otherwise provided for in this chapter, rainwater catchment piping shall be sized in accordance with Chapter 6 for sizing potable water piping.

    1602.0 Nonpotable Rainwater Catchment Systems. 1602.1 General. The installation, construction, alteration, and repair of rainwater catchments systems intended to supply uses such as water closets, urinals, trap primers for floor drains and floor sinks, irrigation, industrial processes, water features, cooling tower makeup and other uses shall be approved by the Authority Having Jurisdiction. Rainwater catchment systems for collecting precipitation from rooftops shall comply with ARCSA/ASPE/ANSI 63. 1602.2 Plumbing Plan Submission. No permit for a rainwater catchment system shall be issued until complete plumbing plans, with data satisfactory to the Authority Having Jurisdiction, have been submitted and approved. 1602.3 System Changes. No changes or connections shall be made to either the rainwater catchment system or the potable water system within a site containing a rainwater catchment system requiring a permit without approval by the Authority Having Jurisdiction. 1602.4 Connections to Potable or Reclaimed (Recy- cled) Water Systems. Rainwater catchment systems shall have no direct connection to a potable water supply or alternate water source system. Exceptions: (1) Potable water, on-site treated nonpotable gray water, or reclaimed (recycled) water is permitted to be used as makeup water for a rainwater catchment system provided the connection is protected by an air gap in accordance with this code.

    (2) A potable water supply may be connected temporarily for the initial cross-connection test of the rainwater catchment system as required in Section 1605.3.2. 1602.5 Initial Cross-Connection Test. Where a portion of a rainwater catchment system is installed within a building, a cross-connection test is required in accordance with Section 1605.3.

  • CPC § 1601.5. High relevance — show source text

    (3) Instructions on maintaining the required water quality as for rainwater catchment systems .

    (4) Details startup, shutdown, and deactivating the system for maintenance, repair, or other purposes.

    (5) Applicable testing, inspection, and maintenance frequencies in accordance with Section 1601.5.

    (6) A method of contacting the installer and/or manufacturer(s).

    (7) Directions to the owner or occupant that the manual shall remain with the building throughout the life cycle of the structure.

    1601.7 Minimum Water Quality Requirements. The minimum water quality for rainwater catchment systems shall comply with the applicable water quality requirements for the intended application as determined by the Authority Having Jurisdiction. Water quality for nonpotable rainwater catchment systems shall comply with Section 1603.4. In the absence of water quality requirements for harvested rainwa- ter, Table 1603.4 shall apply.

    Exceptions:

    (1) Water treatment is not required for rainwater catchment systems used for aboveground irrigation with a maximum storage capacity of 360 gallons (1363 L).

    (2) Water treatment is not required for rainwater catchment systems used for surface, subsurface or drip irrigation. 1601.8 Material Compatibility. Rainwater catchment systems shall be constructed of materials that are compatible with the type of pipe and fitting materials, water treatment, and water conditions in the system. 1601.9 System Controls. Controls for pumps, valves, and other devices that contain mercury that come in contact with rainwater supply shall not be permitted. 1601.10 Separation Requirements. Underground rainwater catchment service piping shall be separated from the building sewer in accordance with Section 609.2. Treated nonpotable water pipes shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where horizontal piping materials do not meet this requirement, the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the treated nonpotable water piping. 1601.11 Abandonment. Rainwater catchment systems that are no longer in use, or fail to be maintained in accordance with Section 1601.5, shall be abandoned. Abandonment shall comply with Section 1601.11.1 and Section 1601.11.2.

    1601.11.1 General. An abandoned system or part thereof covered under the scope of this chapter shall be disconnected from remaining systems, drained, plugged, and capped in an approved manner. 1601.11.2 Underground Tank. An underground water storage tank that has been abandoned or otherwise discontinued from use in a system covered under the scope of this chapter shall be completely drained and filled with earth, sand, gravel, concrete, or other approved material or removed in a manner satisfactory to the Authority Having Jurisdiction. 1601.12 Sizing. Unless otherwise provided for in this chapter, rainwater catchment piping shall be sized in accordance with Chapter 6 for sizing potable water piping.

    1602.0 Nonpotable Rainwater Catchment Systems. **1602.1 General.

  • CPC § 1502.3.2. High relevance — show source text

    (2) A potable water supply may be connected temporarily for the initial cross-connection test of the on-site treated non- potable gray water system as provided in Section 1502.3.2. 1506.5 Water Pressure. On-site treated non-potable gray water systems supplying water to water closets, urinals, and trap primers shall be capable of delivering not less than 15 pounds-force per square inch (psi) (103 kPa) residual pressure at the highest and most remote outlet served. Where the

    TABLE 1505.16 MINIMUM RECLAIMED (RECYCLED) WATER SOURCE TESTING, INSPECTION, AND MAINTENANCE FREQUENCY

    DESCRIPTION MINIMUM FREQUENCY*

    Inspect and clean filters and screens, and replace (where necessary). [Every 3 months.]

    Inspect pumps and verify operation. After initial installation and every 12 months thereafter.

    Inspect valves and verify operation. After initial installation and every 12 months thereafter.

    Inspect pressure tanks and verify operation. After initial installation and every 12 months thereafter.

    Clear debris from and inspect storage tanks, locking devices, and verify operation.

    After initial installation and every 12 months thereafter.

    Inspect caution labels and marking. After initial installation and every 12 months thereafter.

    * Note: Frequency is as described in this table, or more frequently as required by manufacturer’s instructions and/or the Authority Having Jurisdiction.

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    ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

    1506.10.3 Deactivation and Drainage. The on-site treated nonpotable gray water system and the potable water system within the building shall be provided with the required appurtenances (e.g., valves, air/vacuum relief valves, etc.) to allow for deactivation or drainage as required for a cross-connection test in accordance with Section 1502.3.

    1506.10.4 Near Underground Potable Water Pipe. On-site treated nonpotable gray water pipes shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where piping materials do not meet this requirement the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the on-site treated nonpotable gray water piping. 1506.10.5 Required Filters. A filter permitting the passage of particulates no larger than 100 microns (100 µm) shall be provided for on-site treated nonpotable gray water supplied to water closets, urinals, trap primers, and drip irrigation system s . 1506.10.6 Disinfection. Where the intended use of onsite treated nonpotable gray water requires disinfec- tion and/or other treatment, on-site treated nonpotable gray water shall be disinfected as needed to ensure the required water quality is obtained at the point of use. Where chlorine is used for disinfection or treatment, water shall be tested for residual chlorine in accordance with ASTM D1253.

  • CPC § 1505.12. High relevance — show source text

    Where horizontal piping materials do not comply with this requirement, the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the treated nonpotable water piping.

    Exception: [DWR] Recycled water supply systems that are within or a part of a building shall comply with Section 1505.12.

    1502.5 Abandonment. Alternate water source systems that are no longer in use or fail to be maintained in accordance with Section 1501.5 shall be abandoned. Abandonment shall comply with Section 1502.5.1 and Section 1502.5.2.

    1502.5.1 General. An abandoned system or part thereof covered under the scope of this chapter shall be disconnected from remaining systems, drained, plugged, and capped in an approved manner.

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    ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

    1502.5.2 Underground Tank. An underground water storage tank that has been abandoned or otherwise discontinued from use in a system covered under the scope of this chapter shall be completely drained and filled with earth, sand, gravel, concrete, or other approved material or removed in a manner satisfactory to the Authority Having Jurisdiction. 1502.6 Sizing. Unless otherwise provided for in this chapter, alternate water source piping shall be sized in accordance with Chapter 6 for sizing potable water piping.

    1503.0 Gray Water Systems. [BSC-CG] Gray water sys- tems shall be verified in accordance with the California Green Building Standards Code (CALGreen), Chapter 5, Division 5.3. 1503.1 General. The provisions of this section shall apply to the construction, alteration, and repair of gray water systems. A city, county, or city and county or other local government may adopt, after a public hearing and enactment of an ordinance or resolution, building standards that are more restrictive than the gray water building standards adopted in this code. For addi- tional information, see Health and Safety Code Section 18941.7.

    (A) All gray water systems shall be designed with a diverter valve to allow the user to direct the flow to the building sewer and either the irrigation field or disposal field, whichever is used. The means of changing the direction flow of the gray water shall be clearly labeled and readily accessible to the user.

    (B) Water used to wash diapers or similarly soiled or infec- tious garments or other prohibited contents shall be diverted by the user to the building sewer.

    (C) Gray water shall not be used in spray irrigation, allowed to pond or runoff and shall not be discharged directly into or reach any storm sewer system or any surface body of water.

    (D) Human contact with gray water or the soil irrigated by gray water shall be minimized and avoided, except as required to maintain the gray water system. The dis- charge point of any gray water subsoil irrigation or sub- surface irrigation field shall be covered by at least two (2) inches (51 mm) of mulch, rock, or soil, or a solid shield to minimize the possibility of human contact.

  • CPC § 1505.14.2.1 High relevance — show source text

    (1) Notify the Authority Having Jurisdiction of the cross-connection.

    (2) The reclaimed (recycled) water piping to the building and its premises shall be shut down at the meter, and the reclaimed (recycled) water riser shall be drained.

    (3) Potable water piping to the building and its premises shall be shut down at the meter.

    (4) The cross-connection shall be uncovered and disconnected.

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    ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

    (5) The building and its premises shall be retested in accordance with Section 1505.14.2.1 and

    Section 1505.14.2.2.

    (6) The potable water system shall be chlorinated with 50 parts-per-million (ppm) chlorine for 24 hours.

    (7) The potable water system shall be flushed after 24 hours, and a standard bacteriological test shall be performed. Where test results are acceptable, the potable water system shall be permitted to be recharged. 1505.14.2.4 Periodic Inspection. Periodic visual inspections of recycled water supply systems shall be required by the recycled water supplier or designee following the procedures in Section 1505.14.2.1. Pursuant to California Code of Regu- lations, Title 22, Section 60316, annual visual inspections shall be required for recycled water sup- ply systems that are within or a part of a building. 1505.15 Minimum Water Quality Requirements for Reclaimed (Recycled) Water. The minimum water qual- ity for reclaimed (recycled) water shall meet the applicable water quality requirements of California Code of Regulations, Title 22, Division 4, Chapter 3 (commencing with Section 60301) for disinfected tertiary recycled water and the appli- cable reclaimed (recycled) water use. The reclaimed (recy- cled) water supplier shall supply water in accordance with permits issued by the State Water Resources Control Board or Regional Water Quality Control Board. 1505.16 Maintenance and Inspection. Recycled water supply systems and components shall be inspected and main- tained in accordance with the manufacturer’s recommendations and/or as required by the Authority Having Jurisdiction. The frequency of testing, inspection, and maintenance shall be in accordance with Table 1505.16. The required inspection and maintenance shall be the responsibility of the property owner, unless otherwise required by the Authority Having Jurisdiction.

    1506.0 On-Site Treated Nonpotable Gray Water Sys- tems.

    1506.1 General. The provisions of this section shall apply to the installation, construction, alteration, and repair of onsite treated nonpotable gray water systems intended to supply uses such as water closets, urinals, trap primers for floor

    drains and floor sinks, above and belowground irrigation, and other uses approved by the Authority Having Jurisdiction.

  • CPC § 1505.10 High relevance — show source text

    1505.10 Hose Bibbs. Hose bibbs shall not be allowed on reclaimed (recycled) water piping systems. Only quick cou- plers that differs from those installed on the potable water system shall be used on the recycled water piping system in areas subject to public access . Quick couplers supplying reclaimed (recycled) water shall be marked with the words: “CAUTION: NONPOTABLE RECYCLED WATER, DO NOT DRINK,” and one of the symbol s in Figure 1505.10.

    Exception: In accordance with Health and Safety Code Sec- tion 8117 and Section 8118, hose bibbs are approved for use in cemeteries supplied with reclaimed (recycled) water. A hose bibb in an area subject to access by the general public shall be equipped with a sign marked “CAUTION: NON- POTABLE RECYCLED WATER, DO NOT DRINK,” and one of the symbols in Figure 1505.10.

    FIGURE 1505.10

    1505.11 Required Appurtenances. The recycled water supply system and the potable water system within the building and the premises shall be provided with the required appurtenances (e.g., valves, air/vacuum relief valves, etc.) to allow for testing as required for a cross-connection test in accordance with Section 1505.14.2 .

    1505.12 Pipe Separation in Trenches . Reclaimed (recycled) water pipes shall be permitted to be run or laid in the same trench as potable water pipes with 12 inches (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where piping materials do not meet this requirement, the minimum horizontal separation shall be increased to 48 inches ( 1220 mm). The potable water piping shall be installed at an elevation above the reclaimed (recycled) water piping. Reclaimed (recycled) water pipes laid in the same trench or crossing building sewer or drainage piping shall be installed in accordance with Section 609.0 and Section 720.0 of this code for water pipes .

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    ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

    dance with Section 1505.14.2.1 through Section 1505.14.2.4. The inspection and testing shall be per- formed by a cross-connection control specialist who has valid certification from a certifying organization recog- nized by the State Water Resources Control Board pur- suant to its Cross-Connection Control Policy Handbook. (1) Written reports of cross-connection inspections and testing shall be performed as provided in California Code of Regulations, Title 22, Section 60316.

    (2) A cross-connection test pursuant to Section 1505.14.2.2 shall be performed on the premises of a recycled water supply system when there is material reason to believe that the potable water system or recycled water supply system separation from _another water supply has been compromised.

  • CPC § 1506.10.3 High relevance — show source text

    1506.10.3 Deactivation and Drainage. The on-site treated nonpotable gray water system and the potable water system within the building shall be provided with the required appurtenances (e.g., valves, air/vacuum relief valves, etc.) to allow for deactivation or drainage as required for a cross-connection test in accordance with Section 1502.3.

    1506.10.4 Near Underground Potable Water Pipe. On-site treated nonpotable gray water pipes shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where piping materials do not meet this requirement the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the on-site treated nonpotable gray water piping. 1506.10.5 Required Filters. A filter permitting the passage of particulates no larger than 100 microns (100 µm) shall be provided for on-site treated nonpotable gray water supplied to water closets, urinals, trap primers, and drip irrigation system s . 1506.10.6 Disinfection. Where the intended use of onsite treated nonpotable gray water requires disinfec- tion and/or other treatment, on-site treated nonpotable gray water shall be disinfected as needed to ensure the required water quality is obtained at the point of use. Where chlorine is used for disinfection or treatment, water shall be tested for residual chlorine in accordance with ASTM D1253.

    1506.11 Valves. Valves, except fixture supply control valves, shall be equipped with a locking feature. 1506.12 Signs. Signs in buildings using on-site treated nonpotable gray water shall comply with Section s 1501.9, 1501.9.1 and 1501.9.2 and applicable requirements of the Cal- ifornia Building Code . 1506.13 Inspection and Testing. On-site treated nonpotable gray water systems shall be inspected and tested in accordance with Section 1502.1 and/or as required by the Authority Having Jurisdiction .

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    water pressure in the on-site treated non-potable gray water supply system within the building exceeds 80 psi (552 kPa), a pressure reducing valve reducing the pressure to 80 psi (552 kPa) or less to water outlets in the building shall be installed.

    1506.6 Initial Cross-Connection Test. A cross-connection test is required in accordance with Section 1502.3. Before the building is occupied or the system is activated, the installer shall perform the initial cross-connection test in the presence of the Authority Having Jurisdiction and other authorities having jurisdiction. The test shall be ruled successful by the Authority Having Jurisdiction before final approval is granted. 1506.7 On-Site Treated Nonpotable Gray Water Sys- tem Materials. On-site treated nonpotable gray water supply, and distribution system materials shall comply with the requirements of this code for potable water supply and distribution systems unless otherwise provided for in this section.

    1506.8 On-Site Treated Nonpotable Gray Water **Devices and Systems.

  • CPC § 1502.3.3 High relevance — show source text

    (3) The drain on the alternate water source system shall be checked for flow during the test and fixtures, potable and alternate water source, shall be tested and inspected for flow. Flow from an alternate water source system outlet indicates a cross-connection. No flow from a potable water outlet shall indicate that it is connected to the alternate water source sys tem.

    (4) The potable water system shall then be depressurized and drained.

    (5) The alternate water source system shall then be activated and pressurized. When an alternate water source is not available for the initial cross-connec- tion test, a temporary connection to a potable water supply shall be required. At the conclusion of the ini- tial cross-connection test, the temporary connection to the potable water supply shall be disconnected.

    (6) The alternate water source system shall remain pressurized for a minimum period specified by the Authority Having Jurisdiction while the potable water system is empty. The minimum period the potable water system is to remain depressurized shall be determined on a case-by-case basis, but in no case shall that period be less than 1 hour.

    (7) Fixtures, potable, and alternate water source shall be tested and inspected for flow. Flow from a potable water system outlet indicates a cross-connection. No flow from an alternate water source outlet will indicate that it is connected to the potable water system.

    (8) The drain on the potable water system shall be checked for flow during the test and at the end of the

    test.

    (9) Where there is no flow detected in the fixtures which would indicate a cross-connection, the potable water system shall be repressurized. 1502.3.3 Discovery of Cross-Connection. If a cross-connection is discovered, the following procedure, in the presence of the Authority Having Jurisdiction, shall be activated immediately:

    (1) Notify the Authority Having Jurisdiction of the cross connection.

    ( 2 ) The alternate water source piping to the building and its premises shall be shutdown at the meter, and the alternate water source riser shall be drained.

    ( 3 ) Potable water piping to the building and its prem- ises shall be shutdown at the meter.

    ( 4 ) The cross-connection shall be uncovered and disconnected.

    ( 5 ) The building and its premises shall be retested in accordance with Section 1502.3.1 and Section

    1502.3.2.

    ( 6 ) The potable water system shall be chlorinated with 50 parts-per-million (ppm) chlorine for 24 hours.

    ( 7 ) The potable water system shall be flushed after 24 hours, and a standard bacteriological test shall be performed. Where test results are acceptable, the potable water system shall be permitted to be recharged. 1502.4 Separation Requirements. Underground alternate water source service piping other than gray water shall be separated from the building sewer in accordance with this code. Pipes carrying treated nonpotable water shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where horizontal piping materials do not comply with this requirement, the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the treated nonpotable water piping.

  • CPC § 1502.3.1 High relevance — show source text

    (1) Notify the Authority Having Jurisdiction of the cross connection.

    ( 2 ) The alternate water source piping to the building and its premises shall be shutdown at the meter, and the alternate water source riser shall be drained.

    ( 3 ) Potable water piping to the building and its prem- ises shall be shutdown at the meter.

    ( 4 ) The cross-connection shall be uncovered and disconnected.

    ( 5 ) The building and its premises shall be retested in accordance with Section 1502.3.1 and Section

    1502.3.2.

    ( 6 ) The potable water system shall be chlorinated with 50 parts-per-million (ppm) chlorine for 24 hours.

    ( 7 ) The potable water system shall be flushed after 24 hours, and a standard bacteriological test shall be performed. Where test results are acceptable, the potable water system shall be permitted to be recharged. 1502.4 Separation Requirements. Underground alternate water source service piping other than gray water shall be separated from the building sewer in accordance with this code. Pipes carrying treated nonpotable water shall be permitted to be run or laid in the same trench as potable water pipes with a 12 inch (305 mm) minimum vertical and horizontal separation where both pipe materials are approved for use within a building. Where horizontal piping materials do not comply with this requirement, the minimum separation shall be increased to 60 inches (1524 mm). The potable water piping shall be installed at an elevation above the treated nonpotable water piping.

    Exception: [DWR] Recycled water supply systems that are within or a part of a building shall comply with Section 1505.12.

    1502.5 Abandonment. Alternate water source systems that are no longer in use or fail to be maintained in accordance with Section 1501.5 shall be abandoned. Abandonment shall comply with Section 1502.5.1 and Section 1502.5.2.

    1502.5.1 General. An abandoned system or part thereof covered under the scope of this chapter shall be disconnected from remaining systems, drained, plugged, and capped in an approved manner.

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    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

    1502.5.2 Underground Tank. An underground water storage tank that has been abandoned or otherwise discontinued from use in a system covered under the scope of this chapter shall be completely drained and filled with earth, sand, gravel, concrete, or other approved material or removed in a manner satisfactory to the Authority Having Jurisdiction. 1502.6 Sizing. Unless otherwise provided for in this chapter, alternate water source piping shall be sized in accordance with Chapter 6 for sizing potable water piping.

  • CPC § 614.2 High relevance — show source text

    Branch lines may be PFA (perfluoroalkoxy)._ 614.2 All piping for multistation or central dialysis units shall be rigid where possible. All piping and tubing shall be in a neat arrangement. The placement of piping or tubing on the floor is not permitted.

    614.3 All valves shall be located in accessible locations.

    614.4 Piping and valves shall be identified according to their function. 614.5 A means of preventing backwashing or flushing of the system when one or more stations are in operation shall be pro- vided.

    614.6 A continuous audible alarm shall sound at the nurses’ station and remote equipment rooms when the minimum veloc- ity is not maintained, or if backwashing or flushing is attempted while one or more stations are in operation. 614.7 Water treatment equipment and water used for dialysis treatment shall meet the latest edition of American Association of Medical Instrumentations (AAMI)/ISO ANSI/AAMI/ISO 23500-2 and 23500-3, Preparation And Quality Management Of Fluids For Haemodialysis And Related Therapies—Part 2: Water Treatment Equipment for Hemodialysis Applications And Related Therapies and Part 3: Water For Haemodialysis And Related Therapies.

    614.8 A diagram of all piping as installed shall be posted at the nurses’ station and equipment room of all multistation or cen- tral dialysis units.

    615.0 Identification of Potable and Nonpotable Water Lines.

    615.1 Uses Not Permitted.

    615.1.1 [OSHPD 1, 1R, 2, 3, 4 & 5] Nonpotable water shall not be piped for drinking, washing or bathing, wash- ing of clothing, cooking, washing of food, washing of cook- ing or eating utensils, washing of food preparation or processing premises, or other personal service rooms. 615.2 [OSHPD 1, 1R, 2, 3, 4 & 5] Non-potable water sys- tems or systems carrying any other non-potable substance shall be installed so as to prevent backflow or back-siphonage into a potable water system. 615.3 [OSHPD 1, 1R, 2, 3, 4 & 5] Outlets for non-potable water, such as water for industrial or fire-fighting purposes,

    shall be posted in a manner understandable to all employees to indicate that the water is unsafe and shall not be used for drink- ing, washing, cooking or other personal service purposes.

    616.0 Emergency Water Supply. [OSHPD 1] 616.1 For new acute care hospital buildings submitted after the effective date of this code, the hospital shall have an on- site water supply sufficient to operate essential hospital util- ities and equipment in the acute care hospital building, to support 72 hours of continuing operation in the event of an _emergency.

  • CPC § 3.5.2 High relevance — show source text

    pump.

    R309.3.5.2 Required capacity. The water supply shall have the capacity to provide the required design flow rate for sprinklers for a period of time as follows:

    1. Seven minutes for dwelling units one story in height and less than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
    2. Ten minutes for dwelling units two or more stories in height or equal to or greater than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.

    R309.3.5.2.1 Where a well system, a water supply tank system or a combination thereof is used, the configuration for the system shall be one of the following: 1. The water supply shall serve both domestic and fire sprinkler systems. Any combination of well capacity and tank storage shall be permitted to meet the capacity requirement. 2. A stand-alone tank is permitted if the following conditions are met: 2.1. The pump shall be connected to a 220-volt circuit breaker shared with a common household appliance (e.g., range, oven, dryer), 2.2. The pump shall be a stainless steel 240-volt pump, 2.3. A valve shall be provided to exercise the pump. The discharge of the exercise valve shall be piped to the tank, and

    2.4. A sign shall be provided stating “Valve must be opened monthly for 5 minutes.” 2.5. A means for automatically refilling the tank level so that the tank capacity will meet the required water supply duration in minutes shall be provided.

    R309.3.5.3 Connections to automatic fire sprinkler systems. The potable water supply to automatic fire sprinkler shall be protected against backflow by a double check backflow prevention assembly, a double check fire protection backflow prevention assembly, a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly.

    Exception: Where permitted by Section R309.3.1.1, backflow protection for the water supply system shall not be required.

    R309.3.5.3.1 Additives or nonpotable source. Where systems contain chemical additives or antifreeze, or where systems are connected to a nonpotable secondary water supply, the potable water supply shall be protected against backflow by a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly. Where chemical additives or antifreeze is added to only a portion of an automatic sprinkler or standpipe system, the reduced pressure principle fire protection backflow preventer shall be permitted to be located so as to isolate that portion of the system.

    R309.3.6 Pipe sizing. The piping to sprinklers shall be sized for the flow required by Section R309.3.4.2. The flow required to supply the plumbing fixtures shall not be required to be added to the sprinkler design flow.

  • CPC § 601.2.1 High relevance — show source text

    (6) [DWR] Where a public agency requires a building to use recycled water to flush water closets and urinals in accordance with California Water Code 13554. 601.2.1 Submeters. [HCD 1] Submeters (or meters) shall be installed to measure potable and reclaimed (recycled) water (hot and cold) that is supplied for the exclusive use of an individual dwelling unit within a newly constructed, multiunit rental residential structure; or for the use of an individual dwelling unit within a newly constructed mixed-use rental residential/commer- cial structure. Submeters (or meters) shall be installed in accordance with this code and the manufacturer’s installation instructions.

    See Water Code Section 517 for definitions of “multiunit residential structure” and “mixed-use resi-

    dential and commercial structure.” See also Civil Code commencing with Section 1954.201.

    Exemptions:

    (1) Long-term health care facilities as defined in Health and Safety Code Section 1418.

    (2) Low-income housing as defined in Health and Safety Code Section 17922.14 (c)(2)(B).

    (3) Residential care facilities for the elderly as defined in Health and Safety Code Section 1569.2 (p)(1).

    (4) Housing at a place of education as defined in Title 24 of the California Code of Regulations, Califor- nia Building Code, Part 2, Section 202.

    (5) Time-share property as defined in Business and Pro- fessions Code Section 11212, Subdivision (aa).

    601.2.1.1 Approved Submeters. [HCD 1] Sub- meters (or meters) shall be approved in accordance with the Business and Professions Code, Division 5.

    601.2.1.2 Submeter Testing. [HCD 1] Submeter (or meter) testing shall be in accordance with the California Code of Regulations, Title 4, Division 9, Chapter 3, Article 1; Civil Code, Division 3, Part 4, Title 5; and Business and Professions Code, Divi- sion 5.

    601.2.2 Hot and Cold Water Required. In occupancies where plumbing fixtures are installed for private use, hot water shall be required for bathing, washing, laundry, cooking purposes, dishwashing or maintenance. In occupancies where plumbing fixtures are installed for public use, hot water shall be required for bathing and washing purposes. This requirement shall not supersede the requirements for individual temperature control limitations for public lavatories and public and private bidets, bathtubs, whirlpool bathtubs, and shower control valves.

    601.3 Identification of a Potable and Nonpotable Water System. In buildings where potable water and nonpotable water systems are installed, each system shall be clearly identified in accordance with Section 601.3.1 through Section 601.3.5.

    601.3.1 Potable Water. Green background with white lettering.

    601.3.2 Color and Information. Each system shall be identified with a colored pipe or band and coded with paints, wraps, and materials compatible with the piping.

  • CPC § 1505.1 High relevance — show source text

    1505.1 General . . . . . . . . . . . . . . . . . . . . .318

    1505.2 Permit . . . . . . . . . . . . . . . . . . . . . .319

    1505.3 System Changes . . . . . . . . . . . . .319

    xliv 2025 CALIFORNIA PLUMBING CODE

    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    TABLE OF CONTENTS

    1505.4 Connections to Potable or Recycled Water Supply Systems . . . . . . . . . . . . . . . . . . . .319

    1505.5 Water Pressure . . . . . . . . . . . . . . .319

    1505.6 Initial Cross-Connection Test . . . .319

    1505.7 Recycled Water Supply System Materials . . . . . . . . . . . . .319

    1505.8 Recycled Water Supply System Color and Marking Information . . . . . . . . . . . . . . . . . .319

    1505.9 Valves . . . . . . . . . . . . . . . . . . . . . .319

    1505.10 Hose Bibbs . . . . . . . . . . . . . . . . . .320

    1505.11 Required Appurtenances . . . . . . .320

    1505.12 Pipe Separation in Trenches . . . .320

    1505.13 Signage . . . . . . . . . . . . . . . . . . . .320

    1505.14 Inspection and Testing . . . . . . . . .320

    1505.15 Minimum Water Quality Requirements for Reclaimed (Recycled) Water . . . . . . . . . . . . .322

    1505.16 Maintenance and Inspection . . . .322

    Table 1505.16 Minimum Reclaimed (Recycled) Water Source Testing, Inspection, and Maintenance Frequency . . . . . . .322

    1506.0 On-Site Treated Nonpotable Gray Water Systems . . . . . . . . . .322

    1506.1 General . . . . . . . . . . . . . . . . . . . . .322

    1506.2 Plumbing Plan Submission . . . . . .322

    1506.3 System Changes . . . . . . . . . . . . .322

    1506.4 Connections to Potable or Recycled Water Supply Systems . . . . . . . . . . . . . . . . . . . .322

    1506.5 Water Pressure . . . . . . . . . . . . . . .322

    1506.6 Initial Cross-Connection Test . . . .323

    1506.7 On-Site Treated Nonpotable Gray Water System Materials . . .323

    1506.8 On-Site Treated Nonpotable Gray Water Devices and Systems . . . . . . . . . . . . . . . . . . . .323

    1506.9 On-Site Treated Nonpotable Gray Water System Color and Marking Information . . . . . . . . . . .323

Frequently asked questions

Can I run potable and nonpotable pipes in the same trench?

Yes — provided you meet the CPC’s spacing and materials conditions: 12 inches (305 mm) minimum vertical and horizontal separation if both pipe materials are approved for in‑building use, with the potable pipe installed above the nonpotable. If materials don’t meet the requirement, increase the horizontal separation to 60 inches (1524 mm) per § 1601.10.

What if my nonpotable source is reclaimed (recycled) water?

Reclaimed/recycled water trench separation rules are in Chapter 15; recycled water provisions permit the 12 in. separation where materials qualify but raise the increased horizontal spacing in that chapter (see § 1505.12) — check that section and your recycled‑water supplier/AHJ.

Who decides whether pipe materials are “approved for use within a building”?

Approval is determined by the code listings/manufacturer’s approvals and by the Authority Having Jurisdiction (AHJ). If unsure, obtain confirmation from the AHJ before using the reduced 12‑inch spacing.

I can’t find § 609.2 in my copy — is it important?

Yes. § 1601.10 defers some building‑sewer separation details to § 609.2. The uploaded excerpts referenced § 609.2 but did not include its full text, so you should consult the CPC itself or the AHJ for the exact language of § 609.2.

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