Why copper develops pinholes
Copper does not rust the way galvanized steel does, but it can wear thin. Over many years, water chemistry, high flow velocity, turbulence at fittings, stray electrical current and the quality of the original installation can all contribute to small pits that eventually break through. The hole may be smaller than a pencil tip and still soak a wall cavity.
Fullerton's hard water, a blend of local groundwater and imported water, leaves mineral scale that changes how water moves through pipe and fittings. That alone does not doom copper, but in a house where copper has been in service for decades, repeat pinholes are a common reason owners start asking about a repipe.
Where pinhole leaks tend to show up
- A small stain or bubble in drywall below a bathroom or along a hallway.
- Damp baseboards or swollen cabinet bottoms near a sink.
- A warm spot in the floor of a slab home, often from a hot water line.
- A hiss heard in a quiet house at night.
- Green or blue staining at a spot on exposed pipe in the garage or attic.
- A water meter that moves with all fixtures off.
What to do when you find one
- Stop the water.Close the main shutoff. If the leak is clearly on one fixture's line, a fixture valve may be enough.
- Protect the area.Move belongings, mop up, and open the wet area to air if you can safely do so. Wet drywall and insulation can grow mold.
- Photograph and record.Take pictures and note the date and location. A log of leaks helps show whether there is a pattern.
- Get it repaired and examined.Ask the plumber to show you the removed section of pipe and describe its condition.
- Consider the history.If this is not the first, ask whether the leaks share a cause and what replacing that run or the whole system would involve.
Spot repair or repipe
| Situation | Spot repair often fits | Repipe worth discussing |
|---|---|---|
| Number of leaks | First one | Two or more in a few years |
| Location | Same small area | Different rooms or branches |
| Pipe condition when opened | Wall looks thick and clean | Thin, pitted or scaled |
| Pipe location | Accessible wall or attic | Under a slab floor |
Questions after a pinhole leak
- What did the inside of the removed pipe look like?
- Is this pipe Type M or Type L copper, and does that matter here?
- Could pressure, grounding or installation be contributing?
- If this keeps happening, what would a partial or whole-house repipe look like?
Common questions
Can pinhole leaks be sealed from the inside?
Some products and services coat pipe interiors. Ask any provider for details, licensing and written terms, and compare that with replacement before deciding.
Does homeowners insurance cover pinhole leaks?
Policies differ. Some cover water damage but not the pipe repair. Check your own policy and talk to your insurer.
Are pinhole leaks a sign of bad water?
Not necessarily. They usually come from a combination of factors. A plumber can look at the pipe; the city's water utility can answer questions about the water supply.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.