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

Hydrostatic Water Test

Going one step further than the hydrostatic water test on the previous page you can also choose to plug the skimmer and return lines with rubber winterization plugs to further isolate the plumbing system from the pool structure.

In most cases simply running the filtration for 24 hours and then turning it off for 24 hours and recording the water level differences can be enough however you may want to take your test this extra step. With the return lines and skimmer lines physically plugged, this would drastically reduce the potential leak points should the water level continue to drop even with the plumbing ports sealed at the pool walls.

Plugging Skimmer & Return Lines

Even if the pool stops leaking during the period of time where the ports are plugged this also lets you focus on the likely locations for the leak. You can pull just the skimmer plugs or just the return plugs to see if you can further diagnose where the water is escaping the system.

Depending on how you run your hydrostatic tests you may have the pool filtration system shut down for extended periods of time.. During the time when the pump is off the pool water can begin to turn green due to a lack of sanitizer and a lack of filtration. You can offset this by adding liquid chlorine and manually agitating the water with a pool pole and brush.

Structural Leaks

If a structural leak is suspected in the pool then I would expect the leak to continue completely unchanged regardless of the condition of the filtration system or whether you are plugging return and skimmer ports or not. Any variation in the rate of water loss while testing the pool would indicate that the problem is not a structural leak as a hole in the liner or crack in the fiberglass or concrete will leak fairly steadily.



The only factors that will really change the rate of water loss for a structural leak is the water level in the pool and the weather conditions, specifically any rain. If the water level drops below that of the leak point then the pool water level will hold constant. If there is a great deal of rain then the ground around the pool can become saturated, or the ground water level can rise above the leak origin, and in both of these cases the rate of water loss would slow or stop.

Plumbing Pipe Leaks

Other than holes in vinyl liner swimming pools, leaking plumbing lines, cracked pool pipes an broken / leaking fittings are the leading cause of water loss in swimming pools. The hydrostatic test serves to identify if the plumbing lines are leaking by isolating them from the pool structure itself.

With the return and skimmer lines plugged off a pool with a plumbing leak should hold water indefinitely. Since the return lines and suction lines are connected via the pump and filter you may not be able to isolate any further than just the say that the leak is somewhere in the plumbing system. Further isolation of the leak will usually require opening the plumbing system to isolate each line even further and even going so far as to conduct a pressure test which is the true test for finding pool plumbing leaks.

Continue now to the hydrostatic test results page to evaluate exactly what your findings indicate about the water loss in your pool



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.