Symptoms
- Small spray or drip from a tiny hole in the pipe surface
- Greenish-blue staining around the leak point
- Leak may be intermittent, worse with higher water pressure
- Pipe otherwise looks intact aside from the pinhole
Likely causes
- CommonPitting corrosion from water chemistry (pH, high chlorine, or aggressive water)Certain water conditions attack copper pipe walls from the inside, eventually wearing through in one small spot.
- CommonHigh water velocity or turbulence at a fittingSharp bends or partially closed valves can cause erosion-corrosion that concentrates wear at one point.
- PossibleManufacturing defect in the original pipeRare thin spots from the manufacturing process can fail years later under normal conditions.
- Less commonStray electrical current (electrolysis) affecting the pipeGrounding issues in the home's electrical system can sometimes accelerate corrosion at specific points on copper pipe.
What to do
- Shut off the water supply to that section of pipe as soon as possible to stop the leak and prevent water damage.
- Dry the area and confirm it's a pinhole in the pipe itself, not a leaking nearby fitting.
- For a quick temporary fix, use a rated pipe repair clamp or epoxy putty rated for plumbing, following the product's instructions closely.
- A pipe repair clamp is meant to be temporary; it buys time but is not a permanent fix.
- Plan for the damaged section of pipe to be cut out and replaced with new copper or an appropriate transition fitting.
- If pinhole leaks have appeared more than once in the same system, consider a broader inspection, since it may indicate a water chemistry issue affecting multiple sections.
- A water treatment specialist can test for pH or corrosivity issues if pinhole leaks recur across different areas of the home.
Tools and parts
- Pipe cutter (for permanent repair)
- Wrench
Pipe repair clamp or copper repair couplingSearch: “copper pipe repair clamp”
When to call a pro
Call a plumber for a permanent repair, and consider a water quality assessment if pinhole leaks recur in multiple spots.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.