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PVC Plumbing Pressure Testing

If your pool is losing water and you have checked and eliminated all 4 possible causes in our previous article, the leak could be in the PVC plumbing.

1. Construct a pressure testing tool as shown in the diagram and connect it to the pool PVC lines.

2. You can test the entire system at once or each PVC line separately. Install a pressure test plug in each return, skimmer and main drain.

3. Use the attached pressure test tool to put water in the PVC lines. The lines should be mostly full of water and not just air. Remove one of the plugs if necessary to fill the pipes with water then reinstall the plug. Continue to add water until the pressure reaches 20-25 psi.

4. Turn off the valve on the pressure test tool and watch the pressure gauge. If the pressure goes down quickly, there is a leak in the PVC pipe. Be sure and check the pressure test plugs to make sure they are not leaking. If the pressure goes down slowly there is a small leak. If there is no leak the pressure should hold for several hours.

5. If the pressure goes down you will need to test each line individually to locate the leak. If the PVC pipe is under a concrete deck, you can add an air valve to the pressure test tool. Use an air tank or compressor to add air to the water pressurized line. Look for the water bubbling in cracks or use a stethoscope to listen through the deck for the leak.

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  1. Jess says:

    This takes the fear of having a leak. It sounds pretty easy.

  2. Robert says:

    Thanks for the info. You’re never tool old to learn something and this will come in handy in spring when I’m out there fixing pools and plumbing.

  3. Loren says:

    I really like that you showed an expanded diagram with detailed parts breakdown. We build our own leak testing devices and traditionally use flex hose connectors instead of male adapters. I can see both working good though. I’d like to suggestion a blog that we added on our website about leaks and the “Bucket Test”. We have a video that helps you determine if you ever have a leak in your pool. Thanks again for the great blog post! -Loren, Wilmington Pool Service

  4. Larry says:

    I am unable to seal the return jet and the 2 skimmers I have. There is a slight leak at one of the four jets so i lose a lb of water pressure per minute. The skimmer also leaks because i cannot tighten the plug at the bottom of the sklimmer,
    i have used teflon tape with no luck and even tried a pipe lube similar to magic lube with no luck.any tips
    thank you;

  5. Vinyl Tubing says:

    great diagram, really shows how it works. Need to try this.

  6. Scott says:

    You may need to replace the gaskets on the return jets or make sure there is no debris between the gasket and the pool wall. Teflon should work on the skimmer plug however if there in no reason to have to remove the plug later you could glue it in with PVC glue if you can get it completly dry. Another option is to use EZ Patch found at the bottom of this page

  7. Sammy says:

    What kind of plugs do i use and where can i get them ?

  8. thermowell installation says:

    One way that you can do to check you water line is by testing it. This will help you determine where the problem is coming from. Following those things that were mentioned above can be a great help to everyone who would like to perform this kind of task on their own.

  9. Foster says:

    You can use rubber or pvc threaded plugs for plugging on the pool side. You can purchase them anywhere pvc is sold or at your local retailer.

  10. sammy says:

    Thanks for your answers one more quesiton if i use air instead of water is the air psi also 20-25 psi?

  11. Foster says:

    its the same psi but I always use 18psi for about 3 minutes.

  12. James McGough says:

    I need to replace my chlorine generator and will be cutting in some new fittings. What type of rigid PVC do I need? Will the stuff at Lowes work? It is rated for 280 psi at 73°F. The guy at Lowes said I needed high pressure pipe. 280 psi is pretty high. Also what glue to use? The standard PVC primer and cement or other?

  13. Foster says:

    Schedule 40 pvc is what you will need to use. You can get it anywhere pvc is sold. Regular pvc cleaner & cement is fine.

  14. Chris says:

    I don’t seem to lose water but when I vaccume the pool the pump doesn’t stay full. I have two skimmers and two main drains. The skimmers are not connected, only at the manifold(individual lines). I’ve tried both skimmers for vaccuming but same result is the pump reduces to half prime. It happens right when shut other valves and then put vac hose in but not until I put vac hose in. I tried different hoses and same thing. Don’t know what is going on. Please help. Thanks

  15. Foster says:

    Its because the pump isnt that strong and its reducing the waterflow by pulling the water from the hose. As long as your shutting off the valves to everything except the skimmer your vacuuming thru it should still give you enough pressure to vacuum. Also, make sure you are putting your filter on waste.

  16. joyce says:

    The question is how do you fix the leak that is under the deck? Can you just jack hammer out a narrow spot and somehow patch the pipe or do you have to rip up the entire length and completely replace the entire pipe? What in the world made the pipe leak in the first place? It is in Florida, so doubt that it was frozen.

  17. Foster says:

    There are several things that can cause a leak, but the #1 culprit is tension. If the plumber didnt level the pipe when installed, a joint could have had tension that led to a crack or break. The first thing you must do is locate the leak, and that is not an easy task. Once the leak has been located, then you cut out a square about 12×12 & dig down to expose the pipe. Once exposed, you cut out the section that leaking & replace with a U shape made from 4 pvc 90’s and sched. 40 pvc pipe. Making the U shape strengthens the area.

  18. scottuckers says:

    I am regular reader, how are you everybody? This piece of writing
    posted at this website is in fact pleasant.

  19. winnie says:

    we just had a new liner put in our pool, losing a lot of water everyday. I would think before putting the new liner in they would’ve pressure tested the lines first. the reason we got the liner was the water level was very low after a hard winter. the pressure testing was done two weeks after liner was installed. Its a real mess

  20. Thanks for the information. I really like that you showed an expanded diagram with detailed parts breakdown. Hoping to see more of your awesome blogs in the future, keep on blogging!

  21. Leslie king says:

    just wanted to say the tool kit was easy to assemble, but I failed the testing due to leaks from both ends. The 1.5 inch plugs on the other end did not seal leaving tiny leak, the side on the testing tool wasn’t seal. I suspect the female connector from pool has worn out.

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