If you’ve ever dealt with pinhole leaks in copper pipes, you may have noticed something odd, sometimes, those tiny leaks seem to "heal" on their own. While this can feel like a small miracle, it’s really a mix of science and luck. Why it happens is kind of cool, but that it happens means that there is still an issue to address.

What causes pinholes in plumbing?

Pinhole leaks in copper pipes are often caused by a combination of corrosion and hard water. Copper pipes are typically long-lasting, but their inner surfaces can degrade over time, especially in areas with:

  • Hard Water: Water with high levels of minerals like calcium and magnesium can leave deposits inside the pipe. These minerals can create tiny areas of turbulence where corrosion starts.
  • Electrochemical Reactions: Impurities in water, such as chlorine or oxygen, can cause a chemical reaction with copper, weakening the pipe wall.
  • Velocity Damage: High water pressure or flow can erode the copper’s protective inner layer, making it more prone to pinholes.
Pinhole that sealed in a copper pipe in basement.
If you have an older copper pipe system, this might look familiar. Credit: Emily Fazio

Does corrosion naturally fix pinholes in copper pipes?

In some cases, yes. When water escapes through a pinhole, it reacts with oxygen in the air and the pipe’s metal to form oxidation or mineral deposits. These deposits may eventually clog the hole, stopping the leak entirely. The process might turn a steady drip into a fine mist and, finally, into nothing.

While this sounds convenient, it’s not a permanent solution. A pipe weak enough to form one pinhole is at high risk of developing others. Even if the hole seals itself, the pipe wall around it is likely still compromised. Take it from us – we know that when one hole closes or is fixed, it's only a matter of time before a hole appears at a different spot on the same pipe.

A SharkBite fitting is used to fix a copper pipe with a bad leak.
There are a few solutions, but here, we used a SharkBite fitting to replace a small portion of a copper pipe when it experienced a bad leak. Credit: Emily Fazio

What to Do if Your Copper Pipe has Signs of Corrosion

You'll Need:

  • Adhesive Tape or epoxy putty
  • Tube cutter
  • Cotton rags
  • Measuring tape
  • SharkBite fitting or compression fitting
  • Replacement piece of pipe

1. Inspect for Additional Weak Spots

  • Check the entire length of the pipe for white or green corrosion or bluish discoloration. Bulging and evidence of healed pinholes are also evidence of corrosion on copper pipes.
  • A single water leak often signals more corrosion nearby.

2. Address the Immediate Leak

  • If the leak is small and actively dripping, wrap the pipe with plumber’s tape or a pipe repair clamp as a temporary solution.
  • Avoid methods like using adhesive or rubber bands, as these can fail quickly under pressure.

3. Replace the Damaged Section

  • For isolated pinholes, turn off the water supply.
  • Cut out the corroded area using a pipe cutter.
  • Use a SharkBite fitting or another push-to-connect solution to join the two ends. These are user-friendly and reliable for DIY repairs. A compression fitting may be more appropriate for cold water pipes due to the higher pressure they experience.
  • Do not insert short sections of pipe between two fittings, as this increases the chance of future leaks.

4. Replace the Entire Pipe Run if Needed

  • If corrosion is widespread, replace the full length of pipe. The most permanent repair would mean upgrading to PEX or another material less prone to pinholes.
  • Consult a plumber if the damage extends to hard-to-reach areas or multiple pipe runs.

5. Test the Repair

  • Turn the water back on slowly and check for any pipe leaks.
  • Run water at high pressure to ensure the connection holds.

Plumbing in the ceiling includes PEX pipes.
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Is there anything you can do to detect or prevent leaks?

While it’s fascinating that a pinhole leak might temporarily seal itself, this is more of a fluke than a fix. You can add a flow rate valve to adjust the velocity of your cold and hot water pipes. Installing water softener can buy yourself some time. Temporary repairs might hold up for a while. But if corrosion has already taken hold, it will continue to weaken the pipe at different spots, and future leaks are almost guaranteed. 

Address the problem by repairing or replacing the affected pipe. Do regular checks and replace leaky pipes as needed, but remember that, unfortunately, copper pipes won't last forever and eventually will need replacing.