Slab Leaks – What Are They, How to Detect Them, and What to Do

WRITTEN BY: Amelia Ciffone

UPDATED: MAY 12, 2022 | 2 MIN READ

A slab leak occurs when plumbing under your foundation or in the concrete slab your home sits on, springs a leak. If left unattended, slab leaks can lead to ruined flooring, mold, damaged wallboard, or even cracks in foundations. 

Fixing the leaking pipe is fairly easy. Getting to the leaking pipe is difficult and expensive. Obviously, slab leaks can’t be ignored. Here’s how to tell if you have a slab leak and what to do about it.

What Causes Slab Leaks?

There are two major causes of slab leaks, pipes in the foundation bursting and pipes becoming corroded and springing pinhole leaks. Both types have the potential to do serious damage. 

The burst pipe is usually more obvious than a pinhole leak. Burst pipes are more common in older homes. They’re often caused by settling: the older the home is, the more it has settled. Dry weather can also cause slab pipes to burst. During a drought, moisture in the soil evaporates, which can accelerate the settling of your home.

These leaks need to be addressed as soon as they are detected to minimize the property damage and the cost of repair.

Do You Have a Slab Leak? – What to Look For

Dealing with a slab leak early is the best defense you have against major damage and expense. The symptoms of a slab leak can be both subtle or dramatic. Here’s a shortlist of the most common signs you have a slab leak:

  • Higher Water Bill. If you discover that your water bill is higher than normal and you have no obvious reasons for the increase, you may have a slab leak. If your heating bill for the same time period is also higher, then there is a better chance that you have a slab leak. Your furnace needs to work harder to warm the water that is entering the home through the leak.
  • Listening for Leaks. If you are the first one up or the last to go to bed, and you hear water running when everything should be shut off, you may have a slab leak. Listen carefully and track down the source of the noise.
  • Water on the Floor. If you discover water on the floor or unexplained damp spots, you may have a slab leak. The leak will find its way to your floor through the subflooring. These leaks usually appear close to where the plumbing is located such as the kitchen, bathrooms, and the laundry room.
  • Low Water Pressure. If you notice a sudden decrease in water pressure you may have a leak in your main water line (located in the slab or beneath the foundation}. Even a small leak will have an impact on pressure.

What to Do if You Have a Slab Leak

Keep in mind where the leaking pipe is located. To get to it you will have to identify its exact location, go through the flooring, subfloor, and concrete slab. This is not a DIY project and you want to get it done right the first time. 

When you notice a symptom, call a professional plumber to inspect the entire first floor — not just where you suspect the leak is. It may turn out you do have a leak but it’s not under the concrete slab. That would be great news.

If you have a slab leak, the plumber can explain your options and offer a recommendation. You may be able to take advantage of a technique called relining, to fix the pipe without having to trench the entire line. Typically however, re-piping is required which involves the invasive cutting to create access to the leaking pipe, 

Are Slab Leaks Covered By Homeowners Insurance?

The answer to this question is”¬¶maybe. It all depends on your contract, and the best person to consult with is your insurance agent. 

Here’s a rule that applies to all policies. There has to be damage to the dwelling or personal property before a claim can even be submitted. That means you are on the hook for the price of having a plumber inspect the premises. Does that mean you should delay repairing the leak until you have enough damage to make it worthwhile? 

The answer is definitely not. If your insurance company finds out that you’ve done this, all the damage will be classified as negligence, and you won’t be covered. 

The key to minimizing slab leak costs is early detection and repair. You may wind up paying for the whole project so keep the cost as low as you can.

If the leak was caused by a covered peril, damage to the dwelling and personal property will be covered (less deductible). Standard homeowners insurance will often cover the cost of tearing out and replacing the slab so that the plumbing system can be repaired — but most policies won’t pay to repair or replace the plumbing system itself.

In addition, if the cause of the leak was due to tree root invasion, normal wear and tear, or negligence, it won’t be covered.

Your best bet is to contact your agent as soon as you spot a symptom so they can guide you through the process of inspection and repair.