DIY Pool Repair

How To Find Swimming Pool Leaks

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• Home
  Swimming Pool Leak Detection
• Pool Resources
  List of swimming pool resources - Must read for any pool owner
• Signs of damage
  Obvious deficiencies can be a significant possibility for water loss
• Water loss characteristics
  Has the leak developed slowly over time or suddenly over a short period of time
• Pool plumbing systems
  Understanding your plumbing system is critical in being able to diagnose a leak in your swimming pool
• Hydrostatic test
  Learn how to monitor water loss and conduct a hydrostatic test for your pool
• Test Analysis
  Analyze the data from this leak detection test to find out where your pool is leaking
• Condition 1
  Leaking the same with plumbing system on and off
• Condition 2
  Leaking more when plumbing system is on, but water loss in both conditions
• Condition 3
  Leaking more when plumbing system is off, but water loss in both conditions
• Condition 4
  Leaking when plumbing system is on, not leaking when it is off
• Condition 5
  Leaking when plumbing system is off, but not leaking when it is on
• Leak detection test 2
  Another easy method to determine where your pool is leaking
• Water Level Test conclusions
  Analyze the results of the water level leak detection test
• Faceplates & Gaskets
  water level holds anywhere where gaskets or faceplates are touching the waterline
• Skimmer & Mid Wall
  water level below skimmer mouth but above return outlets
• Return Outlets
  water level holds at the height of wall returns
• Indefinite Drop
  water level continues to drain down past wall returns or lower
• Leak Detection Dye Test
  Use colored dye to locate leaks in your swimming pool
• Common Pool Leak Points
  Breakdown of pool components prone to failure and associated water loss symptoms
• Hole In the Liner
  See symptoms associated with a hole in the liner of your swimming pool
• HRV Failure
  Hydrostatic relief valve failure symptoms
• Filter Head Gasket
  Filter head gasket alignment is a common location for unexplained water loss
• Leaking Skimmer
  See symptoms associated with a leaking or cracked skimmer
• Leaking Return Lines
  See symptoms associated with leaks in the swimming pool return lines

Leaking & Cracked Skimmers

Should the skimmer be leaking, there are a few conditions which can appear in the regular operation of your pool system which may help to confirm that the skimmer is the origin of the problem. Cracks in the skimmer can be a common cause of water loss, often resulting from shifting soil conditions or improper winter maintenance.



Since water accumulates in the skimmer, it can freeze in cold conditions and cause tremendous outwards pressure that can crack the skimmer itself. Close visual inspection will help to determine if you have a crack in your skimmer. Should the leak be underground, often the point at which the suction line connects to the bottom of the skimmer, this leak will manifest itself as an increased difficulty in priming the pool pump on start up.

If your pump location is higher than the water level in the pool, this priming difficulty will become more apparent as the leak in the skimmer line worsens. If your pool pump is located lower than water level, your pump should be significantly easier to prime even if there is a small to moderate leak point in the skimmer line. In this common situation, an excess of bubbles or air present in the pump sight glass can indicate that the suction line is pulling air from somewhere.

Note that most swimming pool pumps have a small amount of air entrapped in the top of the sight glass during operation, so a leaking skimmer would increase the amount of air seen in the system. Leaking pump seals, winterizing plugs, gaskets and O-rings on the pump can also independently cause the condition of excess water in the pump sight glass.

Skimmer Hydrostatic Test

If you suspect that your skimmer may be cracked but are unable to visually identify the location, you can use a hydrostatic test to determine if the skimmer body remains structurally sound. To complete this test you will need to lower the water level of the pool below the mouth of the skimmer, as well as plug any open ports in the bottom of the skimmer with a suitable rubber expandable plug, or a threaded winterizing plug with silicon tape as a gasket on the threads.

Simply fill the skimmer to capacity, mark the exact water level with a pencil, and monitor any water loss over a period of time. If the water is escaping, it can only be doing so through the body itself as the bottom ports have been isolated from the plumbing system. A dye test will be able to show you exactly where the water is going. Beware that your plugs are not slowly leaking and giving you false readings with this test. If in doubt, replace the plugs again and repeat the test for accuracy in your findings.




The menu on the right is a chronological step by step process to determine where a swimming pool is leaking. This website is written as a readthrough technical assistance guide for locating leaks. When you believe you have identified where the pool is leaking you need to go to our sister website to see pictures and learn more about the actual swimming pool leak repair process.