Pools are meant to be watertight but over time leaks may develop as your pool shifts, settles, and ages. A pool can leak through its fittings, equipment, plumbing, or even right through the shell. It is important to repair leaks, not only to save water, heat, and chemicals, but also to prevent undermining pool structural components by washing away fill dirt.
How do you know if you have a leak? The most obvious way to tell is if your water level is going down. This doesn’t necessarily mean you have a leak though. Pools naturally lose water to evaporation, splash-out, and backwash waste water. It’s easy enough to rule out splash and waste by simply not using the pool. Now we’ll rule out evaporation.
The Bucket Test
Before doing this test check your weather forecast, you don’t want it too rain and you don’t want it too windy or your results will be invalid.
Turn off your auto filler if you have one. With the pump off – Take a large bucket and put two strips of masking tape lengthwise on the bucket, one on the inside and one on the outside. Fill the bucket with pool water and mark the level on the inside piece of masking tape. Now place the bucket in the pool as deep as you can without immersing it and mark the water level on the outside strip of masking tape. Your steps are a good place for this. (If you don’t have steps you may have to get a little creative. Perhaps put a stepladder in the pool and set the bucket on top.) Wait 24 hours then mark the new water levels on the inside tape and outside tape and measure the differences. If the pool loses more water than the bucket (plus or minus 1/8” or so), you have a leak. A difference of only 1” on a 24’ X 12’ pool is a 180 gallon a day leak!
Let’s find out where the leak is. Not all leaks can be fixed by yourself but there a few things you can check before calling for service. Refill your pool and mark your full level on the inside of your pool with a grease pencil and answer these questions. Reset your bucket test and do it again with the pump running.
Is the pool leaking only with the equipment on?
This may indicate a pressure-side return leak. With the filter pump on, the force of water on the pressure side can open up small drips into spraying gushers. Check the waste or backwash line for water consistently running.
Are there leaks at the equipment pad?
Look closely at the filter, pump, heater, and valves. Check the ground for moisture. Turn the pump on and off looking closely for spraying water when the pump is turned off.
Are there any wet areas around the pool?
Take a walk around the pool's edge and between the pool and the equipment pad. Check for wet soil and eroded areas.
Is the pool leaking only with the equipment off?
This can indicate a suction-side leak. With the filter pump on, the plumbing on the suction side is under vacuum. Air can be drawn in through otherwise leaking voids. You may notice air in the pump basket (if you have a clear lid), air bubbling out of the return lines, or air repeatedly built up inside the filter tank. Is the pump basket lid on tight with an o-ring that shows no visible signs of wear?
Does the pool leak all the time?
This does not rule out leaks in the plumbing, but turns a suspicious eye on the shell of the pool. Looking for cracks in the plaster or tears in the vinyl. Look closely at the tile line and look real closely inside of the skimmer(s). The most common leak we fix is a separation between the plastic skimmer and the concrete pool. This is easily fixed with some pool putty. Under water lights are also a common leak spot, especially the conduit that runs from the light niche to the junction box. Filling the opening of the conduit in the back of the light niche with putty, silicone, caulk, or a pool light cord stopper is a way to fix this problem. If you see something that looks like a crack, use some leak locating dye near it with your pump shut off and water still. If there is a leak present the dye will get sucked into the crack.
Does the water seem to stabilize at any particular level?
You may be able to close the skimmer valve and allow the water level to drop below the skimmer. If it keeps going, we can rule out the skimmer (although there can always be more than one leak). Underwater lights are a common leak source. If the water levels at your pool lights dye test around the sconce very carefully. Look for small debris which may have been sucked into the crack or void. This is a good indication of a leak.
Is your pool equipped with a vinyl liner?
If so, there are special considerations. Look for sinkholes where sand under the liner may have washed away. Look for tears or separations around all fittings: skimmer, returns, cleaner line, etc. Pay close attention to steps and corners, where the liner may be stretched more than normal. If an animal had the misfortune to fall into your pool you may notice claw marks (tears) just below the water line. Spending time under water with a mask may be required to find a small leak in the liner. When liners become old they may develop many pinhole leaks. There can always be more than one leak.
If All Else Fails
Leak detection is a highly specialized branch of the industry. A list of independent pool professionals who specialize in leak detection is available at www.PoolLeak.info. Ninety five percent of all phone calls I get from worried pool owners about a leak turn out to be inexpensive to repair. So relax, if you can't take care of the problem yourself a professional will be equipped to do so for you.
Prices for leak detection and repair will vary widely. Charges may be less if you’ve ruled out or narrowed down the leak’s location following the suggestions above. Average charges for detection start around $200 or more depending on the extent of your leak. Higher prices will be charged for below ground work; however, many leaks are fixed within one hour. You may even want to fix the problem yourself once the leak is pinpointed. Many pools leak in more than one area so monitoring is important after any repair is made. There may be additional charges for cutting and replacing concrete and for SCUBA(under-water) work.
Be sure to visit our Leak Detection Section for leak detection and repair items.
