why do I need a hydrostatic pressure test

Why Do I Need a Hydrostatic Plumbing Test During Foundation Repair?

Facing the prospect of foundation repair has you worried about your plumbing. You’ve heard that your plumbing will break during the process. You’ve heard this hydrostatic plumbing term mentioned once or twice but aren’t sure how or why it’s important.

Or you aren’t worried and haven’t heard such stuff but you’re wondering what the deal is with this *thing* called hydrostatic testing. You want to know more about how it *connects* to your foundation (see, that’s a construction joke right there, hopefully, you’ll get it by the end of this article).

Anchor Foundation Repair

At Anchor Foundation Repair, we do hydrostatic plumbing tests during just about every foundation repair project and have performed this test thousands of times. We can explain it to you, no problem!

This article will define and discuss the hydrostatic plumbing test process as it relates to foundation repairs. We will also review when and why it’s important in the foundation repair process.

What Does Hydrostatic Testing Mean?

Some industry-folk call it a hydrostatic plumbing test, some people call it a hydrostatic pressure test. Both terms are accurate and interchangeable. We’re talking about how this test is specifically used in home plumbing during the foundation repair process.

Hydro = water and static = standing still (or not moving). So if you translate, it’s a “standing water test” conducted on the plumbing drain lines under your home.

The main purpose of a hydrostatic plumbing test is to check for breaks in the system, aka leaky pipes. A hydrostatic plumbing test will tell you if the drain line system of your home is *all good*. Or it will find a problem that needs repair under your slab where it’s not visible or obvious that something is wrong.

If there’s an issue to find with yer pipes, the hydrostatic plumbing test will pick it up.

standing water test

Why is Hydrostatic Testing Important in Foundation Repair?

There are several reasons why hydrostatic plumbing tests are important for your home during foundation repair. The big thing with plumbing drain lines and your foundation is that they are intertwined. The house was built with them connected to one another in many places under your home.

Drain lines are set in place before a new foundation is poured and they come up through the foundation surface to the topside and connect to your sinks, toilets, washing machine, and such inside your home. 

When a house experiences foundation settlement and moves or sinks down, it can take the plumbing with it and cause damage and leaks where those drain lines go through the slab or at connecting points between pipes.

leaky pipes

If you have a leak in your drain lines somewhere, it is likely under your foundation or on the area that goes through the slab where you can’t see it or see evidence of the problem.

Knowing if you have leaks is important so that you can get them fixed for the sake of your home’s plumbing and to safeguard your foundation from further damage due to under-slab leaks. Let’s check out 5 reasons when and why hydrostatic plumbing tests are helpful.

1. To Verify Leaks Before Repair

Sometimes leaking pipes under your home are the cause of your foundation problems in the first place. 

Some homeowner’s insurance policies cover foundation repair if it was directly caused by under-slab leaks. This does not apply to every insurance policy and usually is an option that must be added to the policy. You would have to check with your insurance agent about what is covered if anything.

Homeowners might also want to determine if and where leaks might already be present before foundation repair and get preliminary estimates on the plumbing repair costs. That way you will have some idea of what you are dealing with cost-wise for both your foundation repair and plumbing repair.

2. To Check for Leaks After the Home is Raised

We’re not gonna lie, sometimes when a settled home is raised back up to its original elevation, the drain lines can become compromised. In other words, not only can drain lines get messed up on the way down but they can also get messed up on the way back up. This doesn’t happen every time, but it does happen.

You don’t want to go through the whole foundation repair process and leave leaks under your home. Since leaks under your home can potentially cause more foundation problems, it’s in your best interest to get the drain lines repaired. This cuts the chances for foundation movement in the future. 

You really don’t want to have to do foundation repairs again because drain lines were left leaking under your home, right?

new plumbing repairs should be tested with a hydrostatic pressure test

3. To Verify that the Plumbing System Has Been Fully Repaired

When a plumber comes to fix the drain lines, they should check and make sure that they did it completely and got all the leaks. The hydrostatic pressure tests the new plumbing repairs to ensure that it’s all done and done well. It also tests the rest of the system to make sure that another problem isn’t lurking undetected in another area.

If your chosen plumber does not automatically do hydrostatic testing of the repaired drain lines, we strongly recommend that you ask them to do it for your peace of mind.

4. To Prepare for the Next Step of the Foundation Repair Process

For drilled bell-bottom pier foundation repair with Anchor (and possibly other companies but you should verify), a final step in the process involves filling the void under your raised home with extra support material. This is called mud-pumping and it fills in all the empty space under your slab that is now there that wasn’t before the foundation repair. 

Mud-pumping helps to secure and fully support your foundation underneath the whole surface.


For mud-pumping to work right, there can’t be any holes or broken seals in the pipes under your home. Otherwise, the pressurized mud-pumping material (called slurry) would get inside your drain lines through the holes, and then you have a drain line problem again. 

So, using the hydrostatic plumbing test makes sure that your drain lines are sealed up and prepped for the finished step of mud-pumping to take place.

5. To Secure Your Foundation Repair Warranty

We know that under-home leaks can cause foundation problems. Foundation repair contractors don’t want to set themselves up for doing more warranty work than necessary from unrepaired leaks causing more damage to the home’s foundation after a repair job.

Foundation repair companies can require a hydrostatic pressure test after the repairs in order to activate your warranty (and not having one will void your warranty). They might provide the test for you as part of their services. Some companies will suggest that you to do it yourself by hiring a plumber independently, and others might even bury it in the fine print of your warranty. 

Whether it’s done for you by the foundation repair company or done separately by another professional, be sure you keep the proof that it was done if you need to have it to meet warranty requirements.

Check Your Foundation Repair Contract for Hydrostatic Testing

Now that you know why hydrostatic testing is so important during the foundation repair process, you should definitely check your foundation repair contract (when you get to that point) for this service. 

Anchor Foundation Repair Lifetime Warranty and Service Agreement

Find out if you have to get it done separately or if the company you are using does one for you during the repair process. Be sure to check warranty policies too for “fine print” about plumbing.

At Anchor Foundation Repair, you don’t have to worry because we do this every time we raise a foundation. After 35+ years of repairing foundations for Brazos Valley homeowners, we think it’s the right thing and the smart thing to do. It sets up your foundation repair for the most longevity.

This extra step makes us different from other foundation repair companies. We do other stuff too that makes us stand out from the foundation repair crowd. Check out “Anchor Foundation Repair: 4 Service Features That Set Us Apart,” to find out more about our signature method.