Quick answer
Copper pinhole leaks come from internal pitting corrosion, driven by aggressive water chemistry, electrolysis where dissimilar metals meet, or high water velocity scouring the inside of bends. The important thing to understand is that they cluster: a pinhole is a symptom of a condition affecting the whole run, so patching one and waiting usually means patching the next one a few months later.
Common causes
- Aggressive water chemistry pitting the pipe wall from the inside
- Electrolysis where copper meets galvanised or another dissimilar metal without a dielectric fitting
- High water velocity scouring the inside of bends, often from excessive mains pressure
- Poor-quality or thin-wall pipe used at installation
- Flux residue left inside joints during the original soldering
- Pipe in direct contact with concrete or plaster, corroding externally
What you can do now
- 1Mark and photograph each leak with its date — the pattern tells you whether it is spreading
- 2Check mains pressure, since high velocity is a common and fixable contributor
- 3Look at whether leaks cluster on the hot line, which points at temperature and velocity
- 4Do not rely on repair clamps as a permanent answer
- 5Turn the water off at the mains for any leak you cannot contain
When to call a professional
Pinhole leaks usually recur, so re-pipe the affected run rather than patching individual holes. Ask the plumber to check mains pressure and look for mixed-metal junctions at the same time — if the underlying cause is not addressed, the new pipe corrodes the same way. Call urgently for any leak in a ceiling or wall cavity.
Typical cost in Johannesburg
Patch R450 · Re-run from R1,400
Indicative ranges only. We provide written, itemised quotes before any work.
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