# PEX Repiping in San Francisco

> PEX repiping in San Francisco: California code rules for PEX, fitting systems, routing and support, bonding when metal pipe comes out, testing and permits.

URL: https://hilltoprepipesanfrancisco.com/pex-repiping/

New hot and cold supply in crosslinked polyethylene tubing, routed through joists and chases with fewer openings, tested and inspected.

Last Updated: October 30, 2026

- **$8,500 to $28,000** Typical San Francisco-area range for a whole-house PEX repipe, one to three baths; multi-story or hard-access homes can run higher
- **30 days** Minimum UV protection the California Plumbing Code requires of all PEX installed in the state
- **No local ban** San Francisco's plumbing code amendments add no restriction on PEX for water distribution
- **50 psi** Minimum air test pressure, held 15 minutes, where the PEX maker allows an air test

A PEX repipe replaces a building’s hot and cold supply lines with crosslinked polyethylene tubing, run from the main valve to every fixture. [Hilltop Repipe San Francisco](https://hilltoprepipesanfrancisco.com/) offers and manages PEX repiping across San Francisco, Daly City and South San Francisco, with the work carried out by licensed and insured contractors under a plumbing permit and city inspection. The scope can be the whole building, as described on the [whole-house repiping](https://hilltoprepipesanfrancisco.com/whole-house-repiping/) page, or a defined part of it under [partial repiping](https://hilltoprepipesanfrancisco.com/partial-repiping/).

PEX is the newer material in San Francisco’s repipe record. Among 273 DBI permit descriptions from 2021 to 2025 that describe a domestic water repipe, 92 name copper and only 6 name PEX. Among the first PermitSF plumbing permits filed with repipe wording, 15 of 40 were per-unit permits at a single apartment building, mostly reading “repipe water with PEX.” The material has moved from rare to routine in larger buildings, and the questions owners ask about it are practical ones: whether the code allows it, how it is joined, where it can and cannot run, and what changes when metal pipe comes out.

## What happens on the first visit

The visit starts at the meter box and the main valve, where static pressure is measured. San Francisco is served through about 13 pressure zones, so the pressure at one address is no guide to the next, and the fittings and any regulator are chosen on a measured number. From there the existing pipe is traced to each fixture group, and the route for the new tubing is worked out at the same time.

For PEX, the route is the whole question. The visit looks for the long, open corridors a coil can follow: a garage ceiling, a basement, a crawlspace, a closet stacked under a bathroom. It notes what the tubing must stay away from, such as a gas water heater’s flue, recessed light housings and any garage window or vent that lets daylight in. It decides where a manifold could sit, if one is used, so that it stays accessible. It notes where metal pipe will be removed, because that raises a grounding question for an electrician. The result is a written scope naming the PEX system, the layout, the openings, the permit and who patches each opening.

## Is PEX allowed in San Francisco?

Yes. The 2025 California Plumbing Code, which San Francisco adopts with local amendments, lists PEX in Table 604.1 as approved for both building supply and water distribution. A full-text search of San Francisco’s amendments finds no local restriction on PEX; the city’s changes to the water chapter deal with dielectric fittings, valves and air chambers. The state code does add rules of its own:

- All PEX installed in California must have at least 30-day UV protection, and joints are made according to the manufacturer’s instructions.
- Push-fit fittings must comply with ASSE 1061, and brass fittings used with PEX must meet NSF/ANSI 14, which covers resistance to dezincification.
- PEX-AL-PEX, the aluminum-layered composite, is not adopted for drinking water in housing.
- PEX placed in soil for drinking water must be sleeved with a material impermeable to solvents and petroleum.
- The two-flush, one-week tagging procedure applies to PEX only as the first piping in new construction, so it does not add a week to a repipe.

The [guide to whether PEX is allowed in California](https://hilltoprepipesanfrancisco.com/guide/is-pex-allowed-in-california/) covers the code history. For the material choice itself, the [PEX vs copper guide](https://hilltoprepipesanfrancisco.com/guide/pex-vs-copper/) sets out the tradeoffs, and [copper repiping](https://hilltoprepipesanfrancisco.com/copper-repiping/) covers the metal alternative.

## Fitting systems: expansion, crimp and clamp

A PEX repipe is only as good as its joints, and PEX is joined by a system rather than by a universal technique. Expansion fittings are used with PEX-A: the tube end is stretched, slipped over the fitting and allowed to shrink back until it grips. Crimp and clamp fittings compress a metal ring over the tube on a barbed fitting, and can be used with PEX-A or PEX-B depending on the system. The [PEX-A vs PEX-B guide](https://hilltoprepipesanfrancisco.com/guide/pex-a-vs-pex-b/) compares the two tube types.

The practical rule is consistency. A scope should name one listed system, and the tubing, fittings, rings and tools should come from that system, so that every joint is made to one maker’s instructions. Barbed insert fittings narrow the bore at each joint, which is one reason a long trunk is sized with the fittings in mind rather than by tube size alone.

## Expansion, support and routing

PEX grows and shrinks with temperature far more than copper does. A hot line that runs tight between two fixed points can bow, tick against framing or pull at a fitting as it heats and cools. Good PEX work leaves gentle slack in long runs, uses offsets or loops where a run is long and straight, and holds the tubing with hangers that let it slide rather than pinching it. Supports go at the spacing the maker specifies, and tubing that passes close to the face of a stud or joist gets a steel nail plate so a later drywall screw cannot reach it.

Freezing is not what governs these routes in San Francisco: NOAA’s normals for downtown record no nights at or below 32 F in an average year. Heat and light are. Tubing is kept clear of flue pipes and recessed fixtures, and away from daylight at garage windows and vents. Insulation on hot lines in an open garage is about heat loss and the wait for hot water, not freeze protection.

## Manifold or trunk-and-branch

PEX allows two layouts. Trunk-and-branch follows the old system, with a main line and tees to each fixture group. A home-run manifold gives each fixture its own line from a central valve board, which means more tubing and fewer hidden joints, and an accessible shutoff for every fixture in one place. In a San Francisco house with the mains on a garage ceiling, as in much of the [Sunset and Parkside](https://hilltoprepipesanfrancisco.com/service-areas/sunset-parkside/), a manifold can sit in the garage with home runs climbing to each fixture. In stacked flats, a manifold can sit in each unit, which also helps meet the city’s rule that every unit can be shut off without interrupting the others; the [apartment building repiping](https://hilltoprepipesanfrancisco.com/apartment-building-repiping/) page covers riser work.

Layout affects how long hot water takes to arrive, but it does not settle it. A smaller line to a far bathroom holds less cold water than a large trunk, so it clears sooner. A very long run may still need a recirculation line, and tubing in a continuously recirculating hot loop must meet ASTM F876-2015a or better under the California code. The [manifold vs trunk-and-branch guide](https://hilltoprepipesanfrancisco.com/guide/manifold-vs-trunk-and-branch/) goes further.

## Water chemistry and fittings

SFPUC water is soft, with average hardness of 62 ppm and a pH adjusted to about 9.3, and it is disinfected with chloramine. Scale buildup is not a concern for PEX in this water. The questions are about the parts the water touches: the tubing’s chlorine rating and the brass in the fittings. PEX makers publish chlorine resistance ratings for their tubing, and the system chosen is checked against those ratings for continuous hot use. Brass fittings in plastic systems must resist dezincification under NSF/ANSI 14, and every wetted surface in a drinking water system is held to the state’s lead-free limit. The [guide to San Francisco water and your pipes](https://hilltoprepipesanfrancisco.com/guide/san-francisco-water-and-your-pipes/) covers the chemistry.

## Grounding and bonding when metal pipe comes out

Older San Francisco houses often relied on the metal water pipe as part of the electrical grounding system. PEX does not conduct, so replacing metal pipe with PEX can break a path the electrical system was counting on. The California Plumbing Code addresses this directly: where metal building supply piping is used for grounding, its replacement must be of like material. The electrical code requires any metal water piping that stays in the building to be bonded to the service. In practice, a PEX repipe that removes metal pipe includes a note for a licensed electrician to confirm the grounding electrode and bonding, sometimes under a separate electrical permit. Where the buried service line is the electrode, the [water service line replacement](https://hilltoprepipesanfrancisco.com/water-service-line-replacement/) page explains why that run may stay copper.

## Pressure test, inspection and openings

Before any wall closes, the finished system is tested with water at working pressure or above, or with air at 50 psi or more, and held for at least 15 minutes without leakage. Plastic pipe may be air tested only where its maker allows it, and PEX makers may. The city inspector then sees the work under test on a permit filed on PermitSF by a contractor holding the license a San Francisco plumbing permit requires. The DBI permit for a house is $549, or $809 with underground work, and condos and apartment buildings need a separate permit for each unit. The [San Francisco repiping permit guide](https://hilltoprepipesanfrancisco.com/guide/san-francisco-repiping-permit/) covers the steps.

Because PEX bends around obstacles, it usually needs fewer and smaller openings than rigid pipe, but some openings are certain: wherever a line has to reach a fixture inside a finished wall. In a building built before 1979, paint is presumed to contain lead, and in rentals and shared buildings each opening is set up with containment and notice under the city’s lead-safe rules. The [guide to how invasive repiping is](https://hilltoprepipesanfrancisco.com/guide/how-invasive-is-repiping/) shows what the openings look like.

## What a PEX repipe costs

A typical San Francisco-area range for a whole-house PEX repipe is $8,500 to $16,000 for one bath, $12,000 to $22,000 for two baths and $14,500 to $28,000 for three; multi-story or hard-access homes can run higher. The [repipe cost guide](https://hilltoprepipesanfrancisco.com/guide/repiping-cost/) breaks down what sits inside the price, and the [cost estimator](https://hilltoprepipesanfrancisco.com/tools/repiping-cost-estimator/) gives a range from the baths, floors and material you choose. Homeowners insurance generally responds to sudden water damage under the policy’s terms rather than paying for planned pipe replacement, so a repipe is usually budgeted as an owner’s project.

## What's included

- Static pressure measured at the start, and a pipe map from the main valve to each fixture
- One listed PEX tubing and fitting system used throughout, named in the scope
- Trunk-and-branch or manifold layout, chosen and drawn before work starts
- Hangers and supports at the maker's spacing, with slack and offsets for expansion on hot runs
- Nail plates where tubing passes close to the face of a stud or joist
- Clearance or protection near flues, recessed lights and other heat sources, and no exposure to daylight
- Listed transition fittings at the water heater, the service-line connection and any metal pipe that stays
- A note for an electrician to confirm grounding and bonding once metal water pipe is removed
- Pressure test, flush, fixture stops labeled, and the permit and city inspection before walls close

## Two common ways to join a PEX repipe

|  | Expansion fittings | Crimp or clamp fittings |
| --- | --- | --- |
| Tubing | PEX-A, which expands and shrinks back over the fitting | PEX-A or PEX-B, depending on the system's listing |
| How the joint is made | Tube end is expanded, slipped over the fitting and allowed to recover | A metal ring is compressed over the tube on a barbed fitting |
| Fitting bore | Usually close to the tube's inside diameter | Narrower at each fitting, which matters on long runs |
| Tools | Expansion tool and the maker's heads | Crimp or clamp tool with a go/no-go check |
| Rule that applies to both | Joints made per the manufacturer's instructions (CPC 605.9) | One listed system; tubing and fittings not mixed across makers |

## Related resources

- 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 [Is PEX allowed in California?](https://hilltoprepipesanfrancisco.com/guide/is-pex-allowed-in-california/)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.
- Decision Guide [Should a repipe use a PEX manifold or trunk and branch?](https://hilltoprepipesanfrancisco.com/guide/manifold-vs-trunk-and-branch/)Layout is the repipe decision people hear about last and live with longest. How each design moves water, what it does to the wait for hot water and to shared flow, and which San Francisco buildings suit which.
- Cost Guide [How much does it cost to repipe a house in San Francisco?](https://hilltoprepipesanfrancisco.com/guide/repiping-cost/)Typical San Francisco-area ranges for a whole-house repipe by number of baths, what sits inside the price, the permit fees by city, the programs that help and why two quotes for the same house can differ.

## How a repipe runs

1. The call Describe the building Building type, floors, number of baths and units, the pipe you can see in the garage or basement, and what you have noticed.
2. Walk-through Map the pipe The supply is traced from the meter: pipe map, wall types, the main valve, the water heater and where access is easiest.
3. Scope Written scope and price Material, layout, every planned opening, the permit and who patches what, on paper before work is booked.
4. The work Permit, new lines, pressure test The permit is filed, new lines are run while the old ones still serve, fixtures are switched over and the system is pressure tested.
5. Sign-off Inspection, then patching The city inspector signs off with the pipe still visible. Then the openings are closed.

## What this work looks like

Red and blue PEX trunk lines clipped across the joists of a San Francisco garage ceiling

PEX manifold with red and blue lines rising from a plywood board in a hall closet of a San Francisco flat

Red PEX lines with a brass expansion coupling across garage ceiling joists

Steel nail plate protecting red and blue PEX lines through a notched stud

## PEX repiping questions

### Why does PEX sometimes tick or bow after a repipe?

Because it expands and contracts with temperature far more than copper does. A hot line held tight between two fixed points can bow, or tick against framing, as it heats and cools. Slack in long runs, offsets on long straight stretches and hangers that let the tubing slide prevent most of it. A line that ticks after the job usually needs a support eased or a run rerouted.

### Can sunlight through a garage window damage PEX?

It can over time, which is why the California Plumbing Code requires all PEX installed in the state to carry at least 30-day UV protection and why tubing is kept out of daylight once installed. Runs along a garage ceiling are routed away from windows and vents, or covered where they pass near one.

### Does PEX need to be insulated in a San Francisco garage?

Not to stop it freezing: NOAA's normals for downtown San Francisco record no nights at or below 32 F in an average year. Insulating hot lines in an open garage or crawlspace cuts heat loss and shortens the wait for hot water, and California's energy code requires insulation on newly installed hot water pipe in some work, such as a water heater replacement.

### Are the brass fittings used with PEX lead-free?

They have to be. California limits lead to 0.25%, as a weighted average, on every surface that touches drinking water. Brass fittings used with PEX must also meet NSF/ANSI 14, and brass with more than 15% zinc must resist dezincification, which otherwise leaches zinc out of the fitting and leaves it weak and porous.

### What does a PEX repipe cost in San Francisco?

A typical San Francisco-area range for a whole-house PEX repipe is $8,500 to $16,000 for one bath, $12,000 to $22,000 for two baths and $14,500 to $28,000 for three. Multi-story or hard-access homes can run higher. A DBI house permit of $549, or $809 with underground work, may be included or listed separately.

## Related services

### Whole-house repiping

Every hot and cold supply line from the main valve to each fixture, in PEX or copper, tested and inspected.

Whole-house repiping

### Copper repiping

New hot and cold supply in rigid copper tube, joined by solder or press fittings, with dielectric transitions where it meets steel.

Copper repiping

### Apartment building repiping

Mains, risers and unit branches replaced in occupied flats and apartment buildings, one stack at a time, with a permit for each unit.

Apartment building repiping