First, find out what you have
This single fact changes the whole conversation, and you can usually establish it yourself by looking at exposed pipe in the garage, attic or under a sink.
Galvanized steel. Grey, threaded, magnetic. Common in homes built before about 1960. It corrodes from the inside, so the internal diameter shrinks steadily over decades and rust enters the water. If a house still has galvanized supply, its remaining life is measured rather than estimated.
Polybutylene. Grey, blue or black flexible plastic, usually with stamped markings, installed roughly 1978-1995. It was the subject of one of the largest class-action settlements in US construction history because it becomes brittle and fails at the fittings — frequently without warning, and often inside a wall. Insurers know this, and some will not write a policy on a house that still has it.
Copper. Long lived and generally fine, though our water is hard on it and pinholes appear in older systems.
PEX. Flexible, usually red/blue/white, fitted with crimped rings. Modern, and what most repipes use.
Worth knowing
If you find polybutylene, that alone is worth a conversation regardless of whether it has leaked yet. The failure mode is brittleness at the fittings, and it does not give the gradual warnings that copper and galvanized do.
The signs a system is at the end rather than in need of a repair
One leak is a leak. The distinction that matters is whether the failures are independent events or the same cause showing up in different places.
- Third leak, or second in a year. The rest of the system is the same age under the same conditions.
- Discoloured or rusty water from multiple fixtures, cold as well as hot. From the hot side alone it is the water heater; from both, it is the pipe.
- Low pressure throughout with a healthy regulator and no leak. That is internal diameter lost to corrosion or scale.
- Pinholes in copper. Once one appears, others usually follow in the same run.
- Any polybutylene at all, leaking or not.
- Repairs becoming routine. When you know your plumber's number by heart, the system has told you something.
What the job actually involves
Better than most people expect, and the reason is that modern repipes go overhead rather than through the slab.
New PEX lines are run through the attic and dropped down inside walls to each fixture. The old lines are abandoned in place rather than dug out — there is no reason to excavate a slab to remove pipe that is no longer carrying water.
That means the disruption is drywall rather than concrete: access holes at each drop, which are patched and repainted afterwards. Ask any quote whether drywall repair and paint are included, because that is the most common gap between a quote and a final bill.
Most houses are done in two to five days, with water off for part of each day rather than the whole time. It is inconvenient rather than uninhabitable.
It also permanently removes the supply lines from the slab, which is what stops the slab leak cycle rather than treating it.
When it is not the answer
A repipe is a large job and it is not always the right one. We would rather say so.
One leak in an otherwise sound copper system is a repair. Low pressure caused by a drifted pressure regulator is a $200 part, not a $9,000 job — and that should be checked with a gauge before anyone discusses repiping.
Hot-side-only complaints are the water heater, not the pipes. And a slow drain is drainage, which a supply repipe does not touch at all.
If someone proposes a repipe without having identified your pipe material and taken a pressure reading, get another opinion. Those two facts are the foundation of the recommendation, and they take ten minutes to establish.
The arithmetic that decides it
Set the repipe cost against what you are actually spending. Each leak carries the repair, the drywall or flooring damage, the disruption, and the water lost before it was found.
Three slab leaks handled individually, with floor damage, is comfortably into repipe territory — and at the end of it you still have the pipe that caused them.
There are two other things worth weighing: insurance, which gets difficult on polybutylene and on houses with repeat claims, and resale, where a documented repipe is one of the few plumbing items a buyer's inspector will note favourably.
None of that makes it a small decision. But it is worth doing the sum properly rather than defaulting to the smaller invoice each time.