Why Do Slab Leaks Happen?

Why Do Slab Leaks Happen?

Concrete slab foundations are a popular foundation for homes all over California. These foundations have water, soil, and pipes running beneath them, and over time, those conditions can cause a crack or leak.

Once a pipe in a slab foundation is damaged or the water and soil surrounding it shifts or expands, the slab is weakened and cracks. If a pipe in the slab foundation is damaged, the leaks pour water into the foundation and surrounding soil, causing your home to sink and your floors to become uneven.

Slab foundations are popular in California.

Slab leaks are a common repair for homeowners, but many don’t know about slab leak detection or slab leak repair. Here’s what you need to know.

What is a Slab Leak?

Concrete slab foundations are common for homes all over the country, including California. The concrete is poured in a slab, as the name suggests, and the water supply and drain lines are embedded inside it. This is an economical solution but leaves your slab vulnerable to leaking pipes.

As the pipes age and degrade, the pressure of the water can form cracks and leaks for water to get through. Even a slow leak can saturate the concrete and the surrounding soil, leading to more cracks, more shifting, and more damage.

A slab leak will break apart the concrete foundation.

These leaks often begin small and undetectable. You may only notice there’s a problem as the leak starts to create more damage. Left untreated, however, a small slab leak can compromise your home’s foundation and stability.

Signs You Have a Slab Leak

A lot of homeowners aren’t familiar with slab leaks, but it’s an important aspect of homeownership. Slow leaks build over time, so homeowners may not detect a leak until it causes serious damage.

Here are some signs of a slab leak:

  • High water bills without extra usage of water
  • Cracks or splits in the foundation
  • The sound of rushing water with no open taps
  • Damp spots or discoloration in carpet or hardwood floors
  • Warm spots on floors
  • An odor coming from floors or walls
  • Uneven lawn or plant growth
  • Soil shifting around the home

Why Do Slab Leaks Happen?

A slab leak can happen for many reasons, including:

Bad Construction

Bad construction is the leading cause of slab leaks. Poor quality or damaged pipes and improper installation can cause slab leaks by compromising the integrity of the pipes themselves. Bends, kinks, or poor fittings create weak points for a leak or burst to happen.

The weak spots only get worse over time as water flows through the pipes. All pipes are vulnerable to this damage, but copper pipes are weaker and less durable than other types of pipes.

Soil Shifts

Soil can shift for many reasons, including earthquakes and erosion. When the soil moves, the pipes and the connections are bending and rubbing, damaging them. The vibration of earthquakes can also cause cracks in pipes or force the joints between pipes apart, leading to leaks.

Earthquakes can cause soil shifts which lead to slab leaks.

In addition to the leak itself, the water that pools into the soil from the pipe causes it to moisten and expand or shift more. The pressure builds up and needs somewhere to go, which is usually through the weakest point in the slab. You may notice this as wet spots in your floors, but in some cases, the water can erupt like a geyser and flood.

Poor Water Quality

Poor water quality, such as hard water, can damage your pipes. Hard water contains minerals like magnesium and calcium that leave limescale buildup on your pipes, degrading them over time. Eventually, these pipes leak.

Similarly, water that’s too soft can damage the pipes. A water softener takes the minerals out of hard water, but too much can cause the water to leach minerals from the pipes, weakening them.


Abrasion is a big cause of slab leaks. Pipes rub against hard surfaces like concrete, gravel, and other pipes in the course of use. As time goes on, the friction wears them down more and more, leaving weaknesses for a leak or hole.

Hot water causes pipes to expand as they heat and contract as they cool down, so they rub against these hard surfaces more often. All pipes are vulnerable to the damage from abrasion and friction, however.


Time is the culprit with most home damage and repairs. With the causes on this list, time is part of all of them.

Slab Leak Repair for Your California Home

Older homes may be more vulnerable to slab leaks from copper or galvanized steel pipes, which were once popular but are less durable than newer pipes. The pressure and stress of flowing water also degrades pipes over time and may cause them to leak.

Make sure you call a plumbing professional to take care of your slab leak.

Pipes, like any other part of your home, should be maintained and evaluated regularly to identify any potential problems. Slab leak detection and slab leak repair allow you to catch the issue while it’s small, saving you a lot of money, stress, and hassle in the future.

Call Bell Brothers for your slab leak repairs!