You may know that it’s best to use water to isolate leaking plumbing lines with a pressure test, but do you know why? Check out this video to learn about the pressure testing principles that describe how water and air interact in pool plumbing, and how that impacts your tests to find plumbing leaks.
- Air compresses under pressure, water does not.
This is the primary reason why we recommend using water for a pressure test instead of air. If air and water are both present in the plumbing line during a pressure test, the air will compress under pressure and can slow down the pressure drop you see on your gauge. On a long run of plumbing this can reduce the pressure drop to an imperceptible amount, making a leaking pipe look like it held pressure.
- Air escapes from a leak faster than water does.
You will see a much faster pressure drop when air escapes from a leak than when water does. If you’re trying to get air to a leak to be able to start pinpointing the leak with a listening device, watch for a dramatic drop in pressure. Once this happens you’ll know that air has reached the leak and you can start listening for the telltale bubbling/gurgling noise.
- Water stays low in the plumbing line, air stays high.
Water and air do not stay “mixed” in a plumbing line – the water will always go to the bottom of the plumbing and air will stay high. Even if both water and air are induced at the same time they will separate in the pipe. You won’t make a good leak noise if the leak is in a low part of the plumbing and all of the water above the leak has not been purged. Additionally, you can create distracting noises where air bubbles through water if you’re inducing pressure from the low end of the plumbing.
The Bottom Line
There are two parts to finding leaks in swimming pool plumbing – isolating the leaking line with a pressure test and pinpointing the leak by listening through the pool deck. For effective pressure tests, make sure the line is entirely filled with water. When you’re ready to start listening, make sure that air is reaching the leak in order to make a clear noise.
For more detailed information about pressure testing and sonic pipe leak location, see the corresponding slideshows in our Resource Center. These slideshows provide an in depth explanation of the process and tools used for each test using text annotations and graphics. Don’t hesitate to call us at 800-348-1316 if you have any questions about the material!