# Is PEX allowed in California? > Yes, PEX is allowed in California. What the 2025 California Plumbing Code requires for PEX, repipe vs new-home rules, and how San Francisco applies them. URL: https://hilltoprepipesanfrancisco.com/guide/is-pex-allowed-in-california/ Learn PEX is listed in the California Plumbing Code for drinking water, and San Francisco adds no restriction. The state does attach a few conditions of its own, and one of them works in a repipe's favor. Last Updated: October 30, 2026 Yes. PEX is approved for drinking water throughout California: Table 604.1 of the 2025 California Plumbing Code lists it for both building supply and water distribution, and San Francisco’s local amendments add no restriction. The state attaches a few conditions to PEX, and one of them, the new-construction flushing rule, specifically does not apply to a repipe of an existing house. [Hilltop Repipe San Francisco](https://hilltoprepipesanfrancisco.com/) offers and manages [PEX repiping](https://hilltoprepipesanfrancisco.com/pex-repiping/) in San Francisco, Daly City and South San Francisco under those rules, with the work carried out by licensed and insured contractors who pull the plumbing permit. This guide sets out what the code says, where the idea of a California PEX ban comes from, and which conditions shape a repipe. Key takeaways - The 2025 California Plumbing Code lists PEX, copper, CPVC and PE-RT for water distribution. - San Francisco's amendments touch valves, air chambers and dielectric fittings, not PEX. - All PEX installed in California must have at least 30-day UV protection, and joints follow the maker's instructions. - The two-flush, one-week tagging rule applies only to PEX as the first piping in new construction, not to a repipe. - PEX-AL-PEX is not adopted for drinking water in housing. ## What the California Plumbing Code says California adopts a statewide plumbing code, and the current edition is the 2025 California Plumbing Code. Its Table 604.1 lists the materials approved for building supply and water distribution piping. Copper, CPVC, PE-RT, PEX, stainless steel and several others are marked approved for both uses. PE and PVC are allowed only for building supply and exterior cold water. Any material in contact with drinking water, PEX included, must comply with NSF/ANSI/CAN 61, the standard for health effects of drinking water system components. Lead content of wetted surfaces is limited to a weighted average of 0.25%. So the answer to whether PEX is safe for drinking water in California is the same as for copper: the code accepts products that are certified to those standards. San Francisco adopts the state code with local amendments as the 2025 San Francisco Plumbing Code, in force since January 1, 2026. A full search of those amendments finds none that restricts PEX, PE-RT or CPVC water piping. The local water-piping amendments add a main valve and a shutoff for each dwelling unit, a control valve at each fixture, dielectric fittings where copper meets steel and air chambers at quick-closing valves, and they apply whichever material is used. The [San Francisco repiping permit guide](https://hilltoprepipesanfrancisco.com/guide/san-francisco-repiping-permit/) covers them. ## The conditions California attaches to PEX ### UV protection The code states that all PEX pipe installed in California must provide at least 30-day UV protection. Daylight degrades polyethylene, so tubing is kept covered on site, protected in the building and kept out of windows and open roofs. Makers set their own exposure limits within that rule. ### Joints and fittings PEX joints must be made according to the manufacturer’s instructions, and fittings must be listed in Table 604.1. Brass fittings used with PEX must meet NSF/ANSI 14 so they resist dezincification, and push-fit fittings must comply with ASSE 1061. In practice that means tubing and fittings from one system the maker lists together. The [PEX-A vs PEX-B guide](https://hilltoprepipesanfrancisco.com/guide/pex-a-vs-pex-b/) explains the fitting systems. ### Recirculating hot water and soil Notes to Table 604.1 add conditions for PEX used in continuously recirculating hot water systems, which must meet ASTM F876-2015a or better, and for PEX placed in soil for drinking water. ### PEX-AL-PEX PEX-AL-PEX, tubing with an aluminum layer between two layers of PEX, is listed in the table but not adopted for drinking water by the state agencies that regulate housing. For a house, flat or apartment building, the PEX choices are PEX-A, PEX-B or PEX-C tubing, not the composite. ## The flushing rule, and why a repipe is exempt California has a procedure for PEX in new homes: the system is flushed, filled, left to stand at least a week, flushed again and tagged at each fixture before final approval. The code limits that to PEX “where it is the initial plumbing piping installed in new construction” and says it “shall not apply to the installation of PEX pipe where it replaces an existing pipe system of any material.” A PEX repipe of an existing San Francisco house or flat therefore does not add a week of flushing and tagging. It is still pressure tested before any wall closes, flushed with aerators off, and inspected by the city like any repipe. The [guide to how long repiping takes](https://hilltoprepipesanfrancisco.com/guide/how-long-does-repiping-take/) shows where the real waits are. ## CPVC carries more conditions CPVC is also approved, but inside homes the code lets the local building official authorize it by permit only when the contractor signs a worker-safety certification and a certification to follow the flushing procedure, the system is flushed twice over at least a week with tags at each fixture, enclosed spaces such as low crawlspaces and attics are ventilated or workers wear organic-vapor respirators, and nitrile gloves are used. None of that makes CPVC wrong, but it adds paperwork and schedule that PEX and copper do not, which helps explain why repipes in California are mostly PEX or copper. ## Where the idea of a ban comes from California accepted PEX for homes later than many states, after years of review, and searches for a “California PEX ban” mostly trace back to that period. The code in force today lists it. Homeowners also report older push-fit fittings tagged as not for sale in California and plumbers in other states saying PEX was not allowed where they work. Code status varies by state and city, so a rule from Chicago or an old forum thread says nothing about San Francisco now. A lawsuit over a particular product is not a ruling on the material either: what decides whether a product can be installed is its listing and the code. In San Francisco, PEX is still the less common material on paper. Among 273 DataSF permit descriptions from 2021 to 2025 that describe a water repipe, 92 name copper and 6 name PEX. More recent PermitSF filings include per-unit permits at an apartment building mostly described as repiping with PEX. Either material passes inspection when it is installed to the code and the maker’s instructions; the [PEX vs copper guide](https://hilltoprepipesanfrancisco.com/guide/pex-vs-copper/) covers how to choose. ## Daly City and South San Francisco Both cities are in California, so the state code’s PEX listing and conditions apply there as well. San Francisco’s local amendments do not. South San Francisco’s Building Division states that it enforces the 2025 California codes and requires a plumbing permit with pipe left exposed until it is inspected. Daly City’s permit portal has a “Water Pipe Replacement” permit type, with a rough plumbing inspection before walls are covered. The [Daly City](https://hilltoprepipesanfrancisco.com/service-areas/daly-city/) and [South San Francisco](https://hilltoprepipesanfrancisco.com/service-areas/south-san-francisco/) pages cover each city’s permit office. ## What else a PEX repipe has to account for Replacing metal pipe with plastic changes one thing outside plumbing. Where metal water pipe served as part of the electrical grounding path, the plumbing code requires replacement building supply to be like material, and the electrical code requires any remaining metal water pipe to stay bonded. A licensed electrician confirms bonding after the work. The new system also connects to metal at the water heater and wherever old pipe stays, through listed transition fittings. For the whole picture of what a repipe involves, the [repiping guide](https://hilltoprepipesanfrancisco.com/guide/repiping-guide/) walks through it from the meter to the last patch, and the [whole-house repiping](https://hilltoprepipesanfrancisco.com/whole-house-repiping/) page describes the service. To get a written scope for a PEX repipe of your building, call or send the form. ## Questions about this guide ### Is PEX banned in California? No. Table 604.1 of the 2025 California Plumbing Code lists PEX as approved for building supply and water distribution, and San Francisco's local amendments add no restriction on it. The one PEX product the state does not adopt for drinking water in housing is PEX-AL-PEX, the version with an aluminum layer. ### Does a PEX repipe need the one-week flushing procedure in California? No. The state's two-flush, one-week tagging procedure applies to PEX only where it is the first piping installed in new construction. The code says it does not apply where PEX replaces an existing pipe system of any material, so a repipe of an existing house is exempt. ### Is CPVC treated differently from PEX in the California code? Yes. Inside homes, the local building official authorizes CPVC by permit only under extra conditions: a signed worker-safety certification, the two-flush, one-week tagging procedure, ventilation or respirators in enclosed spaces and nitrile gloves. Those steps add paperwork and time, which is part of why most California repipes use PEX or copper. ## Related service ### PEX repiping New hot and cold supply in crosslinked polyethylene tubing, routed through joists and chases with fewer openings, tested and inspected. PEX repiping ## More guides - Decision Guide [PEX vs copper for a repipe: which should you choose?](https://hilltoprepipesanfrancisco.com/guide/pex-vs-copper/)Both materials are code-approved in San Francisco. The real differences are in how each one travels through a building, what it costs, how it is joined and what has to change around it. - Decision Guide [PEX-A vs PEX-B: what's the difference for a repipe?](https://hilltoprepipesanfrancisco.com/guide/pex-a-vs-pex-b/)Both are crosslinked polyethylene listed for drinking water in California. They differ in how they are made, how stiff they are and which fittings join them, and those differences show up in the walls of an old San Francisco building. - Learn [Do you need a permit to repipe a house in San Francisco?](https://hilltoprepipesanfrancisco.com/guide/san-francisco-repiping-permit/)Yes, and the permit shapes the job: who files it, which fee category applies, when the inspector comes and what the inspector looks for before a single wall is closed. - Learn [Is San Francisco water hard or soft?](https://hilltoprepipesanfrancisco.com/guide/san-francisco-water-and-your-pipes/)The chemistry of Hetch Hetchy water, read for what it does to pipe: why old steel here clogs with rust rather than scale, what chloramine means for material choice, and why the answer changes a little across the county line. - Learn [How does repiping a house work?](https://hilltoprepipesanfrancisco.com/guide/repiping-guide/)The whole picture in one place: what the water supply system is, what San Francisco buildings were piped with and why it fails here, how a repipe is scoped, permitted, installed, tested and lived through, and what to ask before agreeing to one.