How To Tell If Your Sewer Pipe Is Leaking

As we said in our previous post: Sewer Camera Inspection: What It Can and Can’t Find, a plumber cannot perform a sewer camera inspection to determine if you have any leaks in your sewer system.

And if a plumber has told you otherwise, give us a call for a free second opinion.

If you suspect you have a leak in your sewer line, what you need is an under slab sewer leak test. You may have also heard this called a hydrostatic sewer leak test.

How To Perform an Under Slab Sewer Leak Test

Sewer systems are designed to work with gravity, meaning all the pipes are installed at a slight decline. So any water in the sewer pipes runs downhill out of the house through to the main sewer line which is connected to the city’s system or a septic tank.

To test for leaks, we take a rubber, inflatable test ball that is connected to an air hose and insert it into the sewer pipe at the main line cleanout. Once it is in place at the perimeter of your home, we inflate the ball to artificially plug the sewer line so that no water flows past it.

We then go inside the house, pull a toilet from the floor exposing the floor flange—unless you have a dedicated, stand-up shower. In that case, we can use the shower to observe as we would the floor flange.

Then we run the water in the house, from a faucet, to fill the entire sewer system up to slab level and observe the water level at the floor flange for about 20 minutes.

The reason we pull the toilet up and expose the floor flange is to give us a slab level observation point. We can then see if the water level drops or stays at slab level.

Reasons Other Than a Leak

If the water level drops, it might mean you have a leak. But we first want to eliminate any other scenarios that could cause a drop — we call this human error situations.

We go back to the test ball and make sure no water is getting by it. Depending on your system, the plumber can simply look down the pipe and see if any water is running through.

However, if we can’t see down the pipe, this is when a sewer camera comes in handy. We send a sewer camera down the pipe to the test ball location and make sure it’s sealing properly and no water is flowing by it.

If there isn’t any water flowing past the test ball, another possibility we want to rule out are air pockets. To make sure any drops we see in water level isn’t because of air bubbles or pockets, we run the water again to bring it back to slab level and watch for drops.

If the water continues to drop after we’ve ruled out the other possibilities, then we know you have at least one leak under the slab.

What To Watch For With Other Plumbing Companies

If you call a plumbing company and they do any of the following, watch out:

1. They fill up your sewer system with water from the outside with a water hose to test for leaks. Remember, your sewer system works on gravity. So they are trying to push water uphill. We’ve tried this in the past and found it is an ineffective way to test for leaks. After we filled up the sewer pipes from the outside, we ran a sewer camera into the pipes and saw most of the pipes didn’t have any water in them at all.
2. They observe the water level from outside of your house instead of inside. If a plumber tells you you have a leak and never went inside your house, it was impossible for that plumber to know if you have a leak.
3. If you have a sunken tub, or bar sink, or toilet, etc., they use water overflowing as “proof” of a problem and suggest repairs.
4. They use a sewer camera to determine you have and to find leaks.
5. They use scare tactics to try and talk you into repairs as soon as possible.

If any of the above has happened, or anything else that just doesn’t seem right to you, give us a call and we will be happy to talk with you about any questions or concerns you have. We also have a guide for you on how to find a reliable plumbing company to make sure your problem is solved properly.

For another explanation of how to properly test for a sewer leak, check out this video from our YouTube channel to see an example of this:

Free Second Opinion

We know firsthand and from what our customers tell us, there are a lot of plumbing companies out there trying to rip you off. And it’s because of this, we offer a free second opinion test.

If you’re not sure about a test that was done by another Dallas plumbing company or are being pressured into making repairs, give us a call 972-494-1750.