Pinhole Leaks in Copper Pipes: Signs, Causes and What Arlington Homeowners Can Do

A pinhole leak is a very small hole that wears through a copper water pipe from the inside. It may only drip or spray a fine mist, but it runs all day, every day. Many Arlington homes have copper lines in the walls, the attic or under the slab. When a pinhole leak is hidden, the first sign is often a damp spot or a higher water bill. If you think you have one, call (817) 285-5426 for leak detection.

What is a pinhole leak?

A pinhole leak is a tiny hole in a metal pipe, most often copper. It forms when a small spot on the inside of the pipe wears or corrodes faster than the rest. Over time that spot thins until water pushes through. The hole may be smaller than the tip of a pencil.

Because the hole is so small, water often sprays sideways onto the inside of a wall or into the soil under a slab. You may not see any water at all for a long time.

What causes pinhole leaks in copper pipes?

There is rarely one single cause. Common factors include the chemistry of the water, water moving fast through small pipes, pipes that are getting old, and rough cuts or extra solder left inside joints when the pipe was installed. Pipes that rub on wood, metal or concrete can also wear thin from the outside.

• Water chemistry that slowly wears the inside of the pipe
• High water pressure or fast flow in small lines
• Older copper lines
• Burrs or extra solder inside joints from the original install
• Pipes rubbing on framing, straps or the slab

High pressure adds stress to every pipe. Our guide to water pressure problems explains how a pressure regulator works.

What are the signs of a pinhole leak?

Look for small stains or bubbling paint on walls and ceilings, a musty smell, a hissing sound when no water is on, warm spots on the floor if it is a hot water line under the slab, and a water meter that moves when everything is off. Green or blue spots on exposed copper can also mean a pipe is wearing thin.

See our guides to a leak in a wall or ceiling and the musty smell of a hidden leak.

What should I do if I find a pinhole leak?

Turn off the water to that line, or the main shut-off if you cannot isolate it. Dry the area and move anything that can be damaged. A clamp from the hardware store can slow a small leak on an exposed pipe, but it is only a short-term fix. Have the section replaced and the rest of the line checked.

1. Shut off the water to the leaking line or the whole house.
2. Catch the water and dry the area.
3. Take photos for your records.
4. Do a water meter test to see if other leaks exist.
5. Call for leak detection and repair.

Our main shut-off valve guide shows where to find the valve.

If I have one pinhole leak, will I get more?

It is possible. The same water and pipe conditions that caused one hole can affect other parts of the line. One leak does not always mean the whole system is failing. If leaks keep coming back, many homeowners choose to reroute or repipe the worst lines instead of patching one spot at a time.

Compare a spot repair, a reroute and a repipe on our slab leak repair page.

How much does leak detection cost in Arlington?

A basic leak detection visit in Arlington usually costs $150 to $400. If the leak is under the slab, slab leak detection runs about $250 to $600. You get the price before work starts.

General estimates for Arlington, TX in 2026. Your exact price is confirmed before any work begins.