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Hydrostatic Sewer Tests | Why You Need One | Mitchell Property Group

The camera test didn’t show anything was wrong with these 50 year old drain lines. It’s a good thing we did a hydrostatic test. We dodged a $20,000 bullet! Yes, $20,000 is what we spent to fix all the drain lines in this house.
If you buy a house with a slab foundation from me I highly recommend that you have a hydrostatic test performed. I’m talking about the test where they insert a test ball at the cleanout, a toilet is removed and the line is filled with WATER. I’m not talking about pressurizing the line with air. I’m talking about filling it with water which is exactly what the line is designed to do. This is the same test the city of Amarillo performs before they will issue a passing inspection. Some people call this a hydrostatic and some people call it a static test. In Amarillo most people call it a hydrostatic test. It doesn’t matter what term is used what matters is how the test is performed.
About a year ago I started hearing a lot of crazy things being said about hydrostatic testing. One seller told me he had heard that this test would cause sewer lines to explode and buckle the floor. Another seller told me that it would cause a perfectly good line to split right down the middle. You would have thought that plumbers had started using dynamite to test these lines! So I thought I would weigh in and try to dispel some of the most common misconceptions.

1. Hydrostatic tests are only performed in Amarillo. FALSE. They are very common in bigger cities like Dallas and Houston. Many agents in bigger cities are now advising sellers to have them done ahead of time and provide the report to their buyers.

2. Camera tests are just as reliable as hydrostatic tests. FALSE. VERY FALSE! It is impossible to see cracks in some older lines. Often times a camera test shows no problems but when work is done there are cracks found in the drain lines. Also, cameras can’t make 90 degree turns around elbows and p-traps. So you end up only being able to look at some of the lines but not all of them. Finally, most of the time standing water and junk are in the line which makes it impossible to see anything at all. Camera tests are just not reliable. I know from experience!

3. Hydrostatic tests put too much pressure on lines. FALSE. Most hydrostatic tests require filling the lines with water up to approximately 1 foot above the line. For every foot of elevation the water puts .43 lbs of pressure on the line. So the typical test puts .43 psi on the line. In rare instances they fill the water up to 3 feet above grade. This test puts less than 2 lbs of pressure on the line. If they were to fill water up to 10 feet above the line it would still only jump the pressure up to 4.3 psi.

4. Drain lines are not made to withstand this much pressure. FALSE. The burst rate for cast iron is 200 pounds per square inch. The typical hydrostatic test puts .43 psi of pressure on a drain line. Not even close. Also, if this were true, the first time anyone had a sewer back up their drain lines would explode. A sewer back up that causes a toilet to over flow puts more pressure on a drain line than a hydrostatic test. Have you ever heard of a clogged sewer line suddenly exploding? Finally, consider this… Sewer systems are made to hold water when your lines back up. I repeat, they are made to hold water, not just drain water. So how will a test that involves filling the line with water cause any harm?

5. If a pipe has a pre-existing crack a hydrostatic test will cause it to crack more. FALSE. Cast iron pipe that is not packed in dirt has a burst rate of 60 psi. Way below the pressure exerted by a hydrostatic test. If the pipe is packed in dirt (like all sewer drain lines are) the burst rate is even higher. So there is no way that the test is causing more damage. It should also be noted that if a pipe has a pre-existing crack it is already bad. The test is just revealing what is already there.

Over the last 15 years hydrostatic sewer testing has saved my bacon more times than I can count. I know there are different opinions out there and that is fine. I respect everyone’s opinions even if I disagree. I encourage everyone to do their own research and form their own opinions. But form your opinion from facts that are based on physics. Don’t just believe what you hear. The bottom line for me is this… If there is a problem with a house I want you and your family to know about it up front so that I can fix it or you can buy another house. If you buy a slab house from me get a hydrostatic test!

Wade Mitchell
Mitchell Property Group

Mitchell Property Group

Mitchell Property Group


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4105 SW 34th St, Amarillo, TX 79109 | 806-359-7653

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