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Repair & Maintenance

Water Woes: How to Find a Pool Leak

Here’s how to know if your pool is leaking, how to find a pool leak and how to know when it’s time to call in the reinforcements.

How to find a pool leak

Eyeing your pool skeptically these days? Thinking that you could have sworn there was more water in there just the other day? Sure, it’s natural for some water to evaporate. But let’s face it: If you find yourself adding more than two inches of water to your pool each week, you may have a leak. Here’s how to know if your pool is leaking, how to find a pool leak and how to know when it’s time to call in the reinforcements.

First things first: the bucket test.

Before you learn how to find a leak in an in-ground swimming pool, first determine if you have a leak to begin with. Fill a plastic, five-gallon bucket ¾ full of water. Then, use a marker or duct tape to mark where the water line is on the inside of the bucket. Place it in the shallow end of the pool and mark where the water line is on the outside of the bucket. Let it float for two or three days. If the water has gone down the same amount on both sides, that’s merely evaporation. If it’s gone down more on the outside of the bucket, you, unfortunately, have a leak.

The obvious leak.


Signs: Water is leaking all the time; damage is visible around the shell of the pool; moisture on the ground around the equipment pad

Possible sources: Crack in the plaster; tear in the vinyl; broken tile; plastic skimmer is separated from the concrete pool; underwater lights need to be sealed; leak at filter, pump, heater or valves

How to find the leak: If you’re suspicious of a certain spot inside the pool shell, turn the pump off, make sure the water is calm and drop some test dye near it. If it is, indeed, where the leak is, the dye should get sucked in. If you see moisture around the equipment pad, turn the pump on and off, looking for spraying water.

Professional expertise needed: Not necessarily. The shell issues are often fixed with a little pool putty, vinyl patch or cord stopper (if it’s an underwater light). If it’s a leak at the equipment pad, however, it may require professional repairs.

The not-so-obvious leak.

Signs: Swimming pool leaks when pump is off; pool losing water when pump is on

Possible sources: Pressure-side return leak; suction-side leak

How to find the leak: If it’s a pressure-side leak (when the pump is on), you’ll notice water consistently running in the waste or backwash line and “weepers” downhill from the pool. If it’s a suction-side leak (when the pump is off), you’ll notice air in the pump basket or inside the filter tank, as well as air bubbling out of the return lines.

Professional expertise needed: Yes

The sneaky leak.

Signs: Water is leaking all the time; no visible damage found around the pool

Possible sources: Leak in pool plumbing

How to find the leak: Shut off the pump and plug all the lines. If it stops leaking, a pressure test should be performed on the underground pipes.

Professional expertise needed: Yes

The peace of mind.

Of course, if you want to make sure you found the only leak and fixed it once and for all, it’s wise to call in a pool leak expert. Don’t want to bother with the hassle and added costs? View your home warranty information to schedule an inspection and determine which pool parts are covered — and pat yourself on the back for adding your pool to the warranty in the first place.

Related: Money-Saving Tips for Maintaining Your Pool


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