Short definition
A repipe is the systematic replacement of a building’s water-supply piping — cold and hot distribution — when the existing material has reached end of life. The four common triggers are galvanized-steel corrosion, polybutylene (PB) failure, lead service lines, and recurring pinhole leaks in old copper. Most modern repipes use PEX. A whole-house repipe in a 1–3 bathroom Puget Sound home runs roughly $4,500–$15,000 in PEX, more in copper.
What it is
Repiping replaces the supply piping inside the building — and sometimes the service line out to the meter — with new pipe and fittings. It is not DWV replacement (drains, waste, vent), which is a separate scope using different materials.
The decision pattern is failure-mode driven:
- Galvanized steel (1920s–1960s WA homes) corrodes from the inside. Hot supply chokes first; brown water on first draw and steadily falling pressure are the classic tells.
- Polybutylene (gray plastic, roughly 1978–1995) fails at fittings and from chlorine exposure. The class-action settlement is closed; failures are now homeowner-funded.
- Lead service lines (pre-1930 mains) are a health driver, not a failure driver. Federal Lead and Copper Rule Revisions (LCRR) and WA DOH guidance push replacement.
- Copper pinhole leaks — Seattle’s soft, slightly acidic Cedar/Tolt surface water pits Type M copper. Multiple pinholes in a few years usually mean the whole system is on borrowed time.
A modern PEX repipe runs new home-run lines from a central manifold (or branch lines from trunk runs) to each fixture, replaces the angle stops, and abandons the old pipe in place where access is destructive (in slab, behind tile, sealed in walls). Total job cost reflects square footage, story count, fixture count, and how much drywall has to come down.
Why it matters to a homeowner
Repipe is one of the largest plumbing decisions you’ll make. Three things to get right before calling for quotes:
- Confirm the diagnosis. A pinhole leak is not a repipe trigger by itself — it’s a signal. Cut a coupon out of an exposed run and look at the inside wall. Galvanized: rust-tubercle buildup. Copper with pitting: dark dimples. PB: gray plastic with white scaling. The diagnosis decides whether you’re spot-repairing or repiping.
- Pick PEX or copper, then stick with it. PEX is faster, cheaper, more freeze-tolerant, and now dominant in WA repipe work. Copper Type L is the long-life premium option. Mixing systems mid-job creates code and warranty headaches.
- Decide what’s in scope. Service line from the meter to the house? Manifold install in the basement? Replacement angle stops at every fixture? Interior wall demo and patch? Each is a line item that should be specified, not assumed.
A well-scoped whole-house PEX repipe in a typical Puget Sound 1–3 bathroom home runs roughly $4,500–$15,000 (2026); copper roughly doubles that. Multi-story, finished-basement, and full-tile-bath homes are in the upper half. The cheapest quote is rarely the best: scope-shopping the bid against a clear written specification matters more than chasing the lowest number.
When you’ll encounter this term
- Brown water from hot taps and falling pressure across the house — galvanized end-of-life
- A pinhole leak followed by a second one within two years — pattern, not a one-off
- A pre-1995 home with gray plastic supply pipe at the water heater — polybutylene
- A pre-1930 home with the original lead service line — DOH letter or utility-side replacement program
- A plumber’s estimate that lists “demo, repipe, drywall patch, fixture reconnect” line items
Common variants and not the same as
- Whole-house repipe vs. partial repipe. Partial replaces one zone (vertical risers, basement loop, under-slab loop). Whole-house is end-to-end.
- Repipe (supply side) vs. DWV replacement (drains and vents). Different materials, different scope; sometimes done in the same renovation but they aren’t the same job.
- Service-line replacement (utility side, meter to house) vs. interior repipe. Sometimes one drives the other; sometimes they’re separate.
- Home-run PEX manifold vs. trunk-and-branch. Manifold runs an individual line per fixture from a central distribution block — easier to isolate, slightly more pipe. Trunk-and-branch tees off main runs — less pipe, harder to isolate a single fixture.
DIY scope
A handy homeowner with a year-long timeline can repipe a small house in PEX. The labor is straightforward; the patience demand is high. WA jurisdictions generally require a plumbing permit for a whole-house repipe and an inspection at rough-in and trim. Pulling a permit as a homeowner-occupant is allowed for owner-occupied single-family residences; rental and multi-family work has to go through a licensed plumber.
When to absolutely call a pro:
- Service-line replacement under the front yard — utility coordination, right-of-way work, often L&I-licensed contractor required.
- Lead service line removal — health-protective protocol matters for the disturbed lead.
- Multi-story or post-tension slab work — risk of structural and concrete-cutting complications.
Washington note
Two WA-specific factors push repipe decisions:
- Seattle / SPU and Tacoma Water source water is soft and slightly acidic (Cedar / Tolt / Green River surface water). That chemistry pits Type M copper over decades. South Sound and Eastside on different water districts have different profiles. See Seattle tap water.
- Cold-snap freeze events (December 2022, January 2024) repeatedly broke copper risers in unconditioned crawlspaces. PEX’s freeze tolerance — it can swell with ice without rupturing — has become a practical-not-just-cost driver in WA repipe work.
A whole-house repipe in WA typically requires a plumbing permit through your jurisdiction (City of Seattle SDCI, Tacoma Permits, county, etc.) with rough-in and final inspections. Owner-occupants can usually pull the permit themselves; tenants and landlords cannot.