Why So Many La Palma Homes Get Pinhole Leaks

By La Palma Plumber · October 16, 2026

If your neighbors keep talking about slab leaks and repipes, there's a reason. It goes back to when, and how, La Palma was built.

La Palma has an unusual history. It incorporated in 1955 as Dairyland, a city created by dairy farmers who wanted to keep housing tracts out and their cows in. It didn't last. By the mid-1960s the first tracts were going up, the city had renamed itself La Palma, and over the next decade or so the dairies gave way to neighborhoods of single-family homes.

That compressed building boom is why so many La Palma houses are about the same age - and why so many are now having the same plumbing problems.

What a pinhole leak is

A pinhole leak is exactly what it sounds like: a tiny hole in a copper pipe, often no bigger than the tip of a pen. It may start as a slow drip or a fine spray inside a wall, or a damp spot that slowly grows. Because the hole is so small, these leaks can go unnoticed for a long time, especially when the pipe is behind drywall or under a concrete floor.

Why they happen in homes like La Palma's

The pipes are old. Homes built in the 1960s and 70s were mostly plumbed with copper. Copper is a good material, but after 50 to 60 years of water running through it, the walls of the pipe can thin out. When one section fails, other sections of the same age often aren't far behind.

The pipes are under the slab. La Palma's homes are built on concrete slab foundations, and in that era it was common to run water lines beneath or within the slab. Pipes there are hard to inspect, they rub against concrete and gravel as hot water lines expand and contract, and they're exposed to soil that shifts as it gets wet and dries out. A leak under the slab is a slab leak.

Water chemistry. Southern California's water is on the hard side, and the chemistry of what comes through the pipes has changed over the decades. Mineral content, pH, disinfectants and water velocity all affect how copper wears from the inside. Pinhole corrosion is a well-known issue in parts of Southern California, though the exact causes in any one house are hard to pin down.

Hot water lines fail first. Many homeowners notice that the first leaks are on the hot side. Hot water speeds up corrosion, and hot lines expand and contract more, adding wear where they touch concrete.

Signs to watch for

• A warm spot on a tile or wood floor
• The sound of water running when nothing is on
• A water bill that keeps creeping up
• Damp drywall, bubbling paint or warped baseboards
• Green or blue spots on exposed copper pipe, under sinks or at the water heater
• A water heater that runs more than it used to

A simple meter test - turning everything off and checking whether the meter moves - will tell you if water is leaking somewhere. Our leak detection page walks through it.

One leak or many?

This is the big question for La Palma homeowners. A single pinhole leak in an accessible spot is a simple repair. But if your house has had two or three leaks in a few years, or a plumber finds corrosion on several exposed pipes, it usually means the whole system is aging out together.

That's when the conversation shifts from fixing leaks to:

• Rerouting a leaking line through the walls or attic instead of repairing it under the slab. See slab leak repair.
• Repiping the house, often with PEX run overhead, so the plumbing is out of the slab entirely. See repiping.

What you can do now

1. Know your main shutoff. Find it and make sure it turns, so you can stop a leak fast.
2. Check your water bill monthly. A sudden rise is often the first sign.
3. Look at exposed pipes at the water heater and under sinks for green staining or crust.
4. Do a meter test once or twice a year.
5. Keep records of any leaks and repairs - dates and locations. It helps a plumber see patterns and helps you decide between repairs and a repipe.

The neighborhood effect

Because so many La Palma homes were built within a few years of each other, it's common for whole streets to go through the same cycle: one house gets a slab leak, then another, then the repipes start. If your neighbors are dealing with it, it's worth paying attention to the signs in your own home.