What is a Pinhole Leak?

3/14/2019 (Permalink)

Pinhole leaks occur when corrosion inside copper pipes finally breaks through to the outside of the pipe. 

Many homeowners ask, “I thought copper was one of the most durable materials for pipes, how is it they can leak?”

It’s true: copper pipes are frequently used and preferred by plumbers because they’re generally resistant to corrosion and plumbers can easily shape them.

If that’s the case, how can copper pipes leak?

The #1 reason why copper pipes leak is due to turbulence. Turbulence enters your system in 2 ways:

1. Velocity: Plumbing code limits the velocity within your piping system to 8 fps (feet per second) for cold water and 5 fps for hot water. Limiting the velocity reduces the turbulence in the pipes that creates pinholes. 
2. Fittings that are too close together: Fittings that are too close together increase turbulence, which causes pinhole leaks. When fittings are too close together, turbulence in the water flow increases, which means the water grates against the inside wall of the pipe causing it to leak.

Another reason why your copper pipes have leaks is what’s called pitted corrosion, an extremely localized type of corrosion that attacks small areas on the inside surface of copper pipes.

Well, there hasn’t been a conclusive study on what causes pitted corrosion, here are some possible theories:

• High levels of chlorine in the water supply
• Corrosion particles from rusted water heaters
• High water pressure
• High pH levels in the water
• Other chemical factors in soil and water (microbial activity)

How do I know I have pinhole leaks?

If you notice any of the following signs, you may have pinhole leaks…

• Your pipes look dimpled
• The copper is starting to look weathered
• Your water bills are more expensive
• You hear dripping
• You see water stains or discoloration on your walls
• Your home has developed mold or mildew

Those are signs that point to already severe pinhole leaks. A plumber can inspect your piping to confirm you have pinhole leaks. However, because early signs of pinhole leaks are difficult to detect by the naked eye, the best way to check your copper pipes is by having annual plumbing maintenance by a certified plumber.