My Swimming Pool is Leaking

How Do I stop a Swim Pool Leak?

Modern house with swimming pool
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A reader asks: I have an inground swimming pool that is losing water at a rate of about 1/2" a week. I have no idea what the problem is. Can you help me figure out why my swim pool is leaking water?

Spring is the time of year most of us are opening our swim pools, and it is common for people to call in about losing water from a swimming pool. There are some ways you can narrow down the reasons behind your leaky swimming pool.

There are typically one of three swim pool issues with water loss:

  • leaks in the swim pool plumbing
  • leaks in the swimming pool shell
  • excessive splash-out or evaporation from the swimming pool

Excessive Splash-Out or Evaporation

Let's touch on the splash-out and evaporation issue first and see if it can quickly be eliminated. If the pool is not being used frequently (then obviously), it is unlikely that the problem is splash out. On the other hand, if it is the middle of the Summer, with high temperatures and lots of kids getting in and out (dripping wet) this could, in fact, be a real cause.

To eliminate evaporation or splash out pool water loss as causes, here is a quick test that can be run on your swimming pool:

  • Place a 5-gallon bucket on the second step or bench seat and fill it with water so that it is exactly the same level as the swimming pool.
  • If evaporation is the cause of your loss, both levels should drop at the same rate.
  • If the bucket drops faster, you probably have a thirsty dog - so be sure to secure all pets BEFORE the test.
  • If you have a pool leak, then the pool will drop faster than the water level in the bucket.

Once you figure out if you are actually losing water in the pool via a leak, and that is not just evaporating or splashing out, there are a few more tests that can do - but now might be a great time to call in a pool professional to evaluate the situation.

Leaks in Plumbing or the Pool Shell

If you have determined that the swim pool's water loss is due to a leak, there are a few more things you can do to help narrow down the problem:

  • Inspect around the filter pad for obvious leaks.
  • Look for damp spots or drips. A steady drip can result in a lot of water loss over time.
  • Does your pool leak more with the filtration system running vs. not running?

If it does not seem to matter if the pool pump and filter system are on or off, then it is time to start doing checks in the pool:

  • Start "plugging" holes - places like water returns, pool skimmers, and the pool main drains, one at a time.
  • You might want to buy enough winterizing plugs for the returns and the auto cleaner.
  • Try to plug up just the returns first and see if the leak rate slows down.
  • You can screw a plug into the skimmers and see if you notice a water loss change.

Be sure to post some sort of "Pool Closed" sign so no one uses the pool during the tests. Not only can this be detrimental to the testing, it could be dangerous to a swimmer.

If none of those seem to slow down the rate of water loss, you need to call in a leak specialist. These pool professionals specialize in finding and repairing leaking plumbing, etc. Contact your pool service professional, or any swimming pool retail store you frequent, to get references. This is one of those areas that can really get ugly if the person you hire is not competent. Be sure to ask for a few recent references and CALL THOSE REFERENCES before you hire a contractor and they start working. Ask about a particular problem and the timeline for the repairs.

Hopefully, you will be back in perfect condition in time for the many hot Summer days ahead.