Is Hydrostatic Testing Bad For My Foundation?

Hydrostatic testing is a method that tests drain pipes for strengths and weaknesses, such as leaks. No matter how high in quality your pipes are, they don’t last forever. They corrode, joints come apart, they get strangled by tree roots, and they can crack due to the weight of your home and the surrounding soil. When any of these things happen, leaks can result – either under your foundation, in your yard or under slabs.

underground sewer repair

The tricky part is, when this happens, it’s usually out of sight, out of mind. You may not even know you have a leak for months or even years. Despite what you may have heard, hydrostatic testing is an effective method of learning if your pipes are leaking — without causing damage to your house or foundation.

What is a hydrostatic test?

A hydrostatic test is performed to determine if there is a leak in the sewer lines underneath a home’s slab foundation.

First, the main sewer line will be blocked at the clean-out.  Next, the sewer lines will be filled with clean water, typically by removing a toilet inside the house as an observation point and running water from a faucet to fill the entire sewer system up to slab level. Then, the water level is monitored for about 20-30 minutes.  If the water level drops while the system is clogged at the clean-out, this would indicate there is a leak.

Why is a hydrostatic test important?

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’re 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.

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.

How do you know if you need a hydrostatic test?

If you’re buying a new home, you’ll definitely want the home inspected. During inspections, the general home inspector and/or a structural engineer might discover that portions of the home’s foundation might possibly be sagging after taking measurements with a Ziplevel. This could be a sign that the under-slab sewer lines are leaking, as the leaking moisture would cause the soil under the foundation to erode, thereby causing it to sag in certain spots. (This is more common in older homes with cast iron sewer lines.) In instances like these, a hydrostatic test would be needed to determine whether or not a leak might be present.

Can a hydrostatic test damage the plumbing system?

The hydrostatic test in and of itself wouldn’t be the cause if something is damaged during the test. If damage occurs, it is only because something was already broken, i.e. already cracked, and when the system was filled with water the crack was exposed.

No extra pressure is artificially added to the lines other than from the act of filling them up to capacity. The water is not pressurized any further than what normally happens when you fill something up with water. It creates just enough pressure to reveal even the smallest of leaks, but it’s not enough to CAUSE damage that wasn’t already there.

In fact, hydrostatic plumbing tests have been used since the 1970’s. The test is one of the most reliable and effective ways in determining whether or not you’ve got a foundation leak.

What happens if the test fails?

If your home has failed the test, and subsequently perhaps an inspection, you’ll need to get the problem remedied in a timely manner. Leaks only get worse over time, so the quicker the problem is addressed, the better chance you have at mitigating the damage.

Contact L&P Plumbing in Austin

Catching a leak early is the only way to prevent thousands of dollars in costly foundation repair, so don’t delay! Getting a hydrostatic test before foundation repair is well worth it. Contact us today!