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Building Code Reference

Got a CPC 604.1 correction?

Approved water pipe materials

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CPC 604.1 is the California Plumbing Code section that requires water distribution piping to be made from approved materials listed for potable water service. Every pipe, fitting, and joint used to carry drinking water from the meter to fixtures inside the building must appear on the code’s approved materials list. Residential remodels, ADUs, new construction, and any project that touches the supply lines will get flagged if the plan set doesn’t specify code-compliant pipe material by name.

How to fix it

  1. Identify every supply pipe run on the plumbing plan

    Go through the plumbing plan sheet by sheet and mark every segment of water distribution pipe: hot, cold, and recirculation if present. This includes the service entry, main trunk, branch lines to each fixture, and any stub-outs for future use. If the plans show schematic lines without material notes, that’s your correction target. The plan-checker needs to trace every run from meter to fixture and confirm a code-listed material on each segment. Don’t assume any segment is covered by a general note unless the note explicitly references it.

  2. Specify the pipe material and applicable standard by name

    Add a pipe schedule table or keynote legend to the plumbing plan. For each material used, list: the material name (e.g., Type L copper, PEX-A, CPVC), the applicable standard (e.g., ASTM B88 for copper, ASTM F876/F877 for PEX, ASTM D2846 for CPVC), and the NSF/ANSI/CAN 61 listing confirming it’s rated for potable water. “Copper per code” is not sufficient. “Type L copper per ASTM B88, NSF 61 listed” is what the plan-checker wants to see. If you’re using multiple materials in the same project, list them all with separate line items in the schedule.

  3. Address dissimilar material transitions explicitly

    If the project ties into existing pipe of a different material, call out the transition on the plan. Show the transition fitting type (dielectric union for copper-to-galvanized, push-fit transition for PEX-to-copper), and note the standard the fitting meets. Plan-checkers flag undocumented transitions because corrosion at dissimilar metal joints is a leading cause of pinhole leaks in residential supply lines. Spelling it out on the plan removes the ambiguity and prevents the same comment from coming back on the first resubmittal.

  4. Note fittings and joints to the same standard as the pipe

    CPC 604.1 covers the full distribution system, not just the pipe runs. Add a general note confirming that fittings, valves, and joints are listed for potable water service and compatible with the specified pipe material. For PEX, note whether you’re using crimp, clamp, or expansion fittings, and confirm the fitting standard (ASTM F1807 for crimp rings, ASTM F2080 for expansion). A plan that specifies PEX-A pipe but doesn’t address the fitting type will still draw a comment from a thorough plan-checker.

  5. Confirm support spacing per CPC 313.0

    CPC 609.1 requires water piping to be supported per Table 313.3. Add a support spacing note to the plan for each pipe material. Copper horizontal runs: 6-foot maximum for 1-1/2 inch and smaller, 10-foot for 2 inch and larger. PEX horizontal runs: 32-inch maximum for 1 inch and smaller, 4-foot for larger. CPVC: 3-foot maximum for 1 inch and smaller, 4-foot for larger. If the plan-checker is already in CPC Chapter 6 on a 604.1 citation, they’ll often check supports at the same time. Getting both right in the revision saves a round.

  6. Verify pipe is rated for the operating conditions

    Hot water distribution lines need pipe rated for the expected temperature. CPVC is rated to 180°F, PEX to 200°F, and copper handles any domestic hot water temperature you’d set on a residential water heater. If the plans show a recirculation system or a high-efficiency water heater set above 120°F, confirm the selected pipe material can handle the supply temperature. PVC is cold-water only and is not listed for hot water distribution under the CPC. A plan showing PVC on a hot supply run is an immediate 604.1 rejection.

  7. Resubmit with a response-to-corrections memo

    When you resubmit, include a brief response-to-corrections memo: one page, referencing the plan-checker’s exact correction number and stating what was changed and where to find it on the revised sheets. Plan-checkers on resubmittals are often reviewing 10-15 projects at once. A memo that says “Correction 3: Added pipe schedule table to P-1.0, keynotes 5-9” cuts their review time and reduces the chance of the same comment coming back. This is worth the 15 minutes it takes to write.

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Why you got flagged

Plan-checkers flag CPC 604.1 for a handful of consistent reasons, and most of them come down to the same problem: the plumbing plan doesn’t name the pipe material clearly enough.

The most common citation is a plan that calls out piping generically. “Copper or approved equal” has been a standard note on plans for decades, but plan-checkers today want the material called out explicitly: copper Type L, PEX-A, CPVC, along with the applicable ASTM or NSF standard the pipe meets. “Or approved equal” without a listed standard isn’t a material specification; it’s a placeholder.

A second scenario that trips contractors is mixing new and existing pipe without flagging the transition. If you’re adding a bathroom and tying into galvanized iron supply lines, the plan needs to address how the dissimilar materials connect and document that the existing pipe meets current standards or will be replaced. Galvanized iron is still listed for cold water in limited cases, but inspectors will want to see that the plan is deliberate about it, not just silent.

Remodel projects that include a water heater swap often get a 604.1 correction because the plumbing plan only shows the heater location and omits the supply piping material entirely. The plan-checker can’t assume the existing pipe is compliant. If the plans don’t say, they’ll flag it.

ADU projects hit this correction when the designer draws the supply lines schematically without specifying materials. On an ADU the inspector is checking everything from scratch, so a pipe schedule note buried in the spec book isn’t sufficient — the material and applicable listing standard need to appear on the plumbing plan sheet.

The official code

California Plumbing Code — Part 5, Chapter 6: Water Supply and Distribution

Read the source →

Common questions

What pipe materials are approved under CPC 604.1 for potable water?
The California Plumbing Code lists several materials for water distribution, including Type K, L, and M copper (ASTM B88), PEX (ASTM F876/F877), CPVC (ASTM D2846), and brass. Each material must carry an NSF 61 listing confirming it’s rated for contact with drinking water. PVC is NOT listed for hot water distribution — only for cold water in specific drain/waste/vent applications. Galvanized steel is still listed for cold water but rarely used in new construction because of corrosion concerns over time. Check the current California Plumbing Code material tables for the complete listing; the approved materials table is updated each code cycle and a material accepted under a prior edition may not be on the current list.
Can I use PEX for water distribution in California?
Yes. PEX (cross-linked polyethylene) is an approved material under CPC 604.1 and is widely used in California residential construction and remodels. The pipe must meet ASTM F876 or F877, and fittings must meet the applicable ASTM standard for the connection type: ASTM F1807 for crimp rings, ASTM F1960 for cold-expansion, ASTM F2080 for expansion fittings. Your plumbing plan needs to call out the PEX grade (PEX-A, PEX-B, or PEX-C) and the applicable ASTM standard by number. “PEX per manufacturer” without a standard citation will draw a 604.1 correction. Also note that PEX requires UV protection if installed in areas with sun exposure, so outdoor or attic runs need to be sleeved or shielded.
Does CPC 604.1 apply to ADU projects?
Yes, and ADU projects tend to get more scrutiny on plumbing material specifications than typical remodels. An ADU is reviewed as new construction for the dwelling unit, so the plan-checker will verify 604.1 compliance from scratch even if the supply connection ties into existing house piping. The plumbing plan for the ADU needs to call out the pipe material, the ASTM or NSF standard, fittings, and any transitions to existing pipe. If the main house has galvanized supply lines and the ADU will connect to them, address that transition explicitly on the plan. Leaving it unaddressed is one of the most consistent 604.1 corrections on ADU submissions.
My plans say 'copper or approved equal' — is that enough to pass?
No, and that’s one of the most common reasons contractors get a 604.1 correction on resubmittal. “Copper or approved equal” was acceptable shorthand for years, but current plan-check practice requires a specific material call-out. Name the pipe type (e.g., Type L copper), cite the applicable ASTM standard (ASTM B88 for copper), and confirm NSF 61 potable-water listing. If you’re open to more than one material, list them all explicitly in a pipe schedule table rather than using “or approved equal” as a catch-all. The plan-checker isn’t going to make the call for you — they’ll send it back until the plans say exactly what’s going in the ground.
What is the difference between PEX-A, PEX-B, and PEX-C for CPC compliance?
All three grades of PEX are approved under CPC 604.1 as long as they meet ASTM F876. The grades refer to the manufacturing process, not the material safety rating. PEX-A (Engel method) is more flexible and can be used with expansion fittings per ASTM F1960 or F2080. PEX-B (silane method) is the most common grade in residential projects and works with crimp and clamp fittings. PEX-C (electron beam) is less common. For the plan-checker, what matters is that you cite the ASTM pipe standard and the fitting standard; the grade designation is secondary. If you use expansion fittings, call that out specifically because the installation method and fitting sizing differ from crimp systems.
Does 604.1 apply to the water service line coming in from the meter?
Yes. CPC 604.1 covers the full water distribution system, which starts at the point of service connection and runs to every fixture inside the building. The service lateral from the meter to the building is part of that system. On projects where the service line is being replaced or extended, specify the material on the site plan or plumbing plan and confirm it meets the potable water listing requirements. Underground supply lines typically use Type K copper or HDPE (where listed for potable water service) because of soil contact and flexibility requirements. If the existing service lateral is being left in place and not shown on the plans, a general note stating that the existing service line is not part of the scope of work can help avoid the comment.

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