How does a tiny pinhole leak turn into a big plumbing problem? Pinholes may leak continuously or dribble intermittently, apparently sealing themselves only to begin leaking again later. What’s most important about pinhole leaks is not what you see, but what you don’t see. Very often, pinhole leaks in a water supply line are external evidence of much more extensive internal deterioration. No leakage from a water supply line, no matter how insignificant, should ever be considered “normal” and ignored.
The ongoing process of corrosion and pitting inside water supply lines eventually causes an external pinhole leak. While the leakage may appear minor, it’s a major red flag that indicates serious weakening of the pipe. Water pressure inside your household supply lines is anywhere from 45 to 80 psi (pounds per square inch). Corrosion indicated by a pinhole leak could, at any moment, cause the weakened pipe to totally rupture, releasing hundreds of gallons of water and causing severe damage.
Corrosion in water supply lines may occur for several reasons:
- Galvanized steel piping: Once common in residential construction, this kind of pipe is very prone to corrosion over the years and will eventually rupture. If you have old piping in your house, it’s a good idea to have it evaluated by a qualified plumber. If it’s galvanized steel instead of more contemporary copper, PVC or PEX, discuss options for re-piping.
- High mineral content: Minerals in your local water supply — typically calcium carbonate — can accumulate and harden inside the supply lines. This layer of accretion tends to promote corrosion that triggers pinhole leaks and early pipe failure. If pipes are affected by mineral accumulation, replacing the pipes and installing a whole-house water softener will reduce the potential for further damage.
- Water chemistry: Water with a naturally low pH is acidic and tends to accelerate pipe corrosion and pinholes. A plumber can check the pH of your local water supply and offer re-piping options like PVC or PEX that resist acidic corrosion.