The short answer
A pinhole leak in a copper pipe is a tiny hole the water wore through from the inside. In Northern Virginia, one pinhole in an older house is usually a repair: cut out the bad piece and put in new pipe. A second or third pinhole in different parts of the house says the pipe is wearing thin everywhere, and that’s when a repipe starts to make more sense than chasing them one at a time.
Pinholes are sneaky. Most start as a mist or a slow bead inside a wall or a ceiling. The first sign is often a water bill higher than it should be, the sound of water running in the walls, or a stain on the ceiling under a bathroom.
Why copper gets pinholes
Copper corrodes from the inside, slowly, in small pits. Most of the time that’s harmless. A pinhole is one pit that went all the way through. Plumbers see a few usual causes:
- The water itself. How acidic the water is and what it’s treated with change how fast copper pits. That varies from one utility to the next and over time.
- Fast water. Hot water lines on a recirculating pump, and the elbows and tees where water turns hard, wear first.
- Old solder flux. Flux left inside a joint keeps eating at the pipe near it, so pinholes cluster near fittings.
- Thin pipe. Copper comes in wall thicknesses, and Type M, the thinnest, has the least metal to lose.
New copper is printed with a colored stripe: green is Type K, blue is Type L, red is Type M. On old pipe the ink is often gone, and what pipes does my house have shows how to tell what’s in your walls.
Signs of a pinhole leak
- A fine spray or mist inside a wall or a ceiling, sometimes with a hiss.
- A green or white crust on the outside of the pipe at one spot, where water has been seeping and drying.
- A bead of water hanging under a pipe in the basement.
- A water stain on drywall or a ceiling that keeps growing.
- The meter’s leak indicator turning with everything off (how to read it).
A clamp, or cut it out
A repair clamp, a rubber pad and a band bolted around the pipe, stops a pinhole in minutes. It’s a good way to get through the night. It isn’t the repair: the pipe around the hole is just as thin, and the next pinhole can open an inch away.
The repair is cutting out the bad section and putting in new pipe with soldered or press fittings. If you already know something’s leaking, a plumbing visit is $49 in regular hours, and the price of the fix is in writing before we start.
When to repipe
The rule of thumb: one pinhole is a repair. Two or three in different parts of the house within a year or two means the pipe is thinning everywhere, and the next one is coming. Each repair also means opening a wall or a ceiling and patching it. A repipe makes sense when:
- Pinholes keep showing up in different spots.
- The pipe in the basement is green or crusty in a lot of places.
- You’re already opening walls for a remodel.
- The house has other old pipe mixed in, like galvanized or polybutylene (repiping in Northern Virginia).
A repipe runs $1,000 to $12,000: a section under one fixture is an afternoon, a whole house takes longer. From about $17 a month at 0% APR for 60 months, the whole price financed, on approved credit. The new runs are copper or PEX, and PEX doesn’t pit the way copper does.
What it looks like here: whole house repipe in Ashburn, whole house repipe in Chantilly, and a short video on the signs it is time to repipe. For one pipe and its price, see water pipe repair cost.
Finding a pinhole you can’t see
If the meter says something’s leaking and you can’t find it, that’s leak detection: acoustic gear and pressure tests that find the spot, so only one hole gets cut. It runs $200 to $500 (how leak detection works). A leak in the line out in the yard is a different job (a leak between the meter and the house).
Booking a plumbing repair? The whole-house plumbing inspection is included, so the next drip gets caught too.
Get a plumber on it
Book a plumber online, call (703) 997-9757, or book the $29 plumbing safety check. We answer day or night. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What causes pinhole leaks in copper pipes?
Corrosion from the inside. Water chemistry, fast-moving hot water, old solder flux and thin Type M pipe all speed it up, until one pit goes through the wall of the pipe.
Can you fix a pinhole leak with a clamp?
For a night or two, yes. A clamp stops the water but leaves the thin pipe around it. The repair is cutting out that section and putting in new pipe.
How many pinhole leaks before you should repipe?
One is a repair. Two or three in different parts of the house within a year or two usually means the pipe is thin everywhere, and repiping is the fix that stops it.
How much does it cost to repipe a house in Northern Virginia?
$1,000 to $12,000, from one section under a fixture to a whole house. From about $17 a month at 0% APR for 60 months, the whole price financed, on approved credit.
