Pinhole leaks are tiny holes that form in copper pipes when the metal corrodes from the inside. In Arizona, hard water, water chemistry, high water velocity, age and sometimes installation problems all contribute. One pinhole leak often means others will follow. The long-term fix is usually replacing the affected copper or repiping with PEX.
Key takeaways
- Pinhole leaks start as pitting corrosion inside copper pipe.
- Hot water lines and homes 15 to 30 years old are most at risk.
- Clamps are a temporary fix, not a repair.
- Several pinholes in a few years usually means it is time to repipe.
What is a pinhole leak?
A pinhole leak is a very small hole in a copper pipe, often no bigger than a needle point. It starts as a pit on the inside of the pipe wall. Over time, the pit eats through the copper until water sprays or seeps out. Because the hole is so small, it can leak slowly for a long time inside a wall, ceiling or slab before anyone notices.
What causes pinhole leaks in copper pipes?
| Cause | How it contributes |
|---|---|
| Water chemistry | Mineral content, pH and disinfectants like chlorine or chloramine can make water more corrosive to copper. |
| Hard water scale | Mineral deposits create rough spots where corrosion concentrates. |
| High water velocity | Fast flow, often from undersized pipes or high pressure, wears the pipe wall. |
| Heat | Hot water lines corrode faster and expand and contract every day. |
| Installation issues | Excess solder flux, burrs left inside cut pipes, or sharp bends. |
| Electrical issues | Improper grounding through plumbing can speed up corrosion in some homes. |
| Age | Copper installed decades ago has had more time to pit. |
Homes built in the 1980s through early 2000s across the East Valley are now at an age where pinhole leaks are common. Thinner Type M copper, used in many homes, has less wall to lose before it leaks.
What are the signs of a pinhole leak?
- Small water stains on ceilings or walls, often in a line along a pipe route
- A faint hissing sound in the wall when water is not running
- Blue-green stains on copper pipes you can see
- A water meter that keeps moving with everything off
- Warm spots on the floor if the leak is in a hot line under the slab
When the pipe is under the concrete, a pinhole becomes a slab leak. See what a slab leak is and how it is found.
Found a pinhole leak inside a wall? Get the plumbing fixed and the wall cavity dried.
Call: (856) 481-6893How do you fix a pinhole leak?
| Option | When it fits |
|---|---|
| Pipe repair clamp | Emergency stop only, until a plumber can repair it |
| Cut out and replace the section | A single leak in otherwise healthy pipe |
| Epoxy pipe lining | Some systems with early pitting, depending on condition |
| Repipe with PEX | Repeated leaks or widespread pitting |
If you have had two or three pinhole leaks within a few years, ask a plumber about a repipe. Spot repairs on corroding copper often lead to the next leak a few feet away.
Can you prevent pinhole leaks?
- Keep water pressure in a safe range with a working pressure-reducing valve.
- Consider a water softener or treatment system to reduce scale.
- Have a plumber check grounding if leaks keep appearing.
- Check visible copper in the garage and under sinks for green or white crust.
The water damage from a pinhole leak usually costs more than the plumbing repair. Read whether slab leaks are covered by insurance or a home warranty before you file.