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Why do slab leaks happen?

Why Do Slab Leaks Happen?

Concrete slab foundations are a common option for many homes across the US. As an economical solution to construction, slab foundations have pipes and other materials within them to save space and complexity.

Over time, the water that runs through these pipes can leak, damaging the foundation. Even a small crack or leak allows water to flow into the foundation and the soil, leading to shifting of the foundation itself. If left unaddressed, this situation can cause permanent damage to your foundation and your home may begin to sink into the soil.

Though common, many homeowners don’t know anything about slab leak detection, the signs and indicators of a slab leak, or how to go about a slab leak repair.

What is a Slab Leak?

With a concrete slab foundation, the concrete is poured into a slab on the ground and the drain lines and water lines are sealed within it. Many contractors do this to save money, but that does present a possibility of leaks and water damage.

No matter what, pipes will degrade over time. The constant power and pressure of water rushing through them can weaken areas and form fractures and cracks. Big leaks often show with significant water damage or a burst, but even a slow leak can damage the concrete and the soil.

In most cases, homeowners don’t realize they have a slab leak until the damage is severe. This turns a moderate repair into a big and expensive hassle, which is why it’s best to get slab leaks repaired at the first sign.

Signs You Have a Slab Leak

Monitoring your home for slab leaks is a big part of responsible homeownership. Slow leaks only worsen with time, and if you wait until you see a lot of damage, it’s much worse for your home, schedule, and wallet.

Here are some common symptoms of a slab leak:

Why Do Slab Leaks Happen?

Several issues can cause slab leaks, such as:

Poor Construction

Poorly done construction or materials can be a big contributor to slab leaks. Damaged pipes or pipes that are poor quality can lead to leaks. Any bend, kink, weak point, or incorrectly installed joint can create an area for water to break through.

If they start out ok, the pressure of water in the pipes is bound to cause a problem over time. Any pipe will suffer this type of wear and tear, but some pipes like copper are weaker overall and may be more prone to leaks.

Soil Shifts

Soil erodes and shifts because of a variety of issues, including natural disasters like earthquakes. As the soil shifts, the pipes are moved around, bent, or twisted, causing them to bend and rub in ways they shouldn’t. The movement can also cause pipes and joints to disconnect, causing leaks.

Aside from the actual leak, the water that leaks into the soil only worsens the shifting and expansion. The pressure will continue to build in the ground or in the concrete, and eventually, it will come through at a weak point in the slab. This usually appears as wet spots or moldy areas, but it can burst as well.

Poor Water Quality

Bad indoor water quality, such as the hard water common in urban environments, wreaks havoc on your pipes. Many hard minerals are in hard water, such as calcium and magnesium, which leave a buildup on your hair, skin, clothes, and your pipes. Over time, the pipes degrade and leak.

A water softener can certainly help with the hard water, but water that’s too soft isn’t any better. When the minerals are removed from the water, it may seek out minerals from the pipes and leach them out.


Pipes hidden within a foundation experience a lot of friction, not just from the concrete itself, but with other pipes, rocks, tree roots, and more. The friction takes a toll over time, giving the highly pressurized water a spot to break through.

This is worsened by hot water, which causes pipes to expand and contract. When this happens, the pipes rub even harder on surfaces, causing more damage.


Homes naturally come with wear and tear, which includes the plumbing and foundation. You’ll notice that many of the causes of slab leaks have to do with time. Older homes have more of a concern with outdated materials like copper pipes, which are more prone to damage and leaks.

If you suspect you have a slab leak, it’s important to contact a professional plumber for slab leak detection and slab leak repair. This isn’t a DIY project, and the longer you wait, the more damage you could be dealing with.

Need help with slab leaks?  Schedule an appointment with the experts at Proskill!

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