Under Slab Plumbing Leaks – How To Diagnose & Treat Them


Pipe leaks are more than a mild annoyance, because leaks do more than rack up your water bill. Leaks can cause serious damage to your home’s interior and foundation and repair isn’t cheap. On average, leak repair can range from $2,000 to $6,000. Leaks in pipes running throughout the home tend to produce visible problems. However, leaks in pipes running under the home’s foundation can easily go unnoticed and undetected. It’s important for homeowners to know how to diagnose an under slab plumbing leak and treat the problem, as doing so in a timely manner can save you thousands of dollars. 

What Causes Under Slab Leaks? 

Slab leaks typically occur due to the weardown of pipes that naturally takes place over time. Nearly all metals corrode. Even copper, which is fairly resistant to corrosion, often develops pinhole leaks. Movement of the soil and foundation, tree roots, and drastic temperature changes can also stress pipes and lead to a leak. 

How To Tell If Pipes Are Leaking Under Your Slab

Most plumbers advise that a home’s plumbing system should be checked at least once every two years. While leaks are more likely to occur with an older home (usually homes older than 25 years), they can still occur in newer homes as well. There are a few steps you can take to diagnose whether or not your pipes may be leaking under your slab. 

The first thing you should do is check your water bill. If your bills are unusually high and your water consumption hasn’t changed, there’s probably a leak somewhere that is racking up your bill. You can also check for a leak by turning off all of the water in your house and inspecting your water meter. If the pinwheel on the meter continues to spin with the water off, there is probably a leak. More obvious signs of a leak will manifest throughout the house in the form of damp floors, or pools of water around tubs and toilets. If an investigation of your home leads you to believe that a leak may exist, you should call a plumber to perform a test. 

How To Fix Leaking Pipes Under Your Slab

If you suspect a leak in pipes under your slab, it’s important to take immediate action. The faster you can get the pipe fixed, the more you can mitigate damage from the displaced water. As with many repairs, the best solution will depend on a few different factors (mainly the location of the leak and the condition of your pipes). 

In cases where you have minor leaks or pin holes in pipes, you may be able to get away with lining the inside of the pipe with a non-toxic epoxy coating. Adding pipe lining can be an extremely affordable way to repair small issues. 

If there is a single leak in a pipe that is relatively easy to access, a plumber can hack through the concrete to repair the portion of the water pipe or sewer line that is causing the problem. However, if the pipe is in poor condition, repairing one spot of the pipe is only applying a band-aid on a larger long-term issue. For this reason, insurance may require complete repiping to continue coverage if you have homeowner’s insurance. Homeowners often shy away from spot repair as well due to the cost of repairing the flooring and foundation that was hacked away to repair the pipe. 

Complete repiping is generally the preferred solution for both homeowners and their insurance companies. With repiping, the old pipes are left in place and abandoned for new pipes that are routed along the outside edge of the foundation. This solution is more work, but it can often be cheaper than having a professional jackhammer through the foundation concrete only to need that concrete repaired after. 

The total cost to fix pipe leaks under your slab will vary depending on the solution, but you can expect to pay anywhere from under $1,000 to over $10,000. Most, if not all, plumbers offer free quotes, so you’ll be able to get an accurate investment for your fix without having to put money down on the spot. 

Inspecting The Foundation

Fixing under slab plumbing issues is good, but work may not be completed without an inspection of the foundation. Under slab leaks can crack and weaken your foundation. It’s possible you may need your foundation repaired in addition to the pipes. Thus, you may want to pull in a foundation contractor as well as a plumber if a pipe leak is found. Once the pipe is fixed and the foundation is deemed to be secure, you can rest easy knowing your home is safe from peril…for the time being. 


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