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Help! My Pool is losing water

Firstly, you need to determine whether you have a leak or if the water loss is due to evaporation. If you have a Liner Swimming Pool, make sure the water level does not drop too fast or too low as this can cause damage to the Liner. If this does happen add more water and give us a call (or contact your local Pool company). 

There are two ways to check whether you have a leak, by marking the water level of the Pool or by doing a Bucket Test.

Marking the water level

Mark the Pool with a piece of tape at the Skimmer and leave the system off for 24-hrs. If the water level drops more than ¼” (0.6cm is normal evaporation for one day), then you have a leak. If the water drops less than ¼”, then its most likely to be evaporation.

If you have confirmed you have a leak, the next step is to find where it is. There can be many reasons for a leak to develop and below we have listed the most common source and how to fix it.

  • Plant Equipment – Can you see any wet patches around the Filter, Pump, Pipe Valves and joints etc or the Pool?
  • Check the Filtration System. With the Pump running, can you see bubbles in the return line? If so, the Filtration System has a leak in the suction side. Make sure the lid of the Pump Basket is on correctly and the ‘O’ Ring has lubricant and hasn’t perished. If the water level drops continuously whilst the Pump is running, check the backwash or waste line as this means its leaking on the return side.
  • If you don’t see anything obvious, turn off the Filtration System and see where the water level drops to;
  • If it drops to the bottom of the Skimmer opening, it is likely to be leaking from the Skimmer or Filtration System.
  • If the level drops to the light, then the leak is most likely to be due to the light fitting/housing.
  • If the level drops below the light, this could mean the Main Drain is leaking or the Pool shell itself.

If you think the leak is caused by the Skimmer, Lights or Liner, have a good look for tears, gaps or cracks or anything that looks misaligned.  With the Pump off and the water still, place a drop or two of a Leak Detector Dye next to the suspected area and see if it’s sucked in. If it is, this area is the culprit! To fix;

  • Skimmer – leaks are often caused by a gap between a Concrete Tiled Pool and the Plastic Skimmer and can usually be fixed with Pool Putty.
  • Lights – a more difficult fix as it is often the conduit pipe that has broken, separated or come apart but it can be done with a two-part epoxy, putty or silicone.
  • Liner – use a Vinyl repair patch kit. Make sure it is suitable for underwater if needed. 

Bucket Test

This test exposes water in a bucket to the same conditions as those affecting your Pool. By comparing the water loss in each, you can determine if the Pool is leaking or the water is evaporating. Fill a bucket with water from the Pool to about 3” from the top and put a weight in it (a brick or rock will suffice), and set it on a step. If you don’t have a walk-in step unit, you should be able to float the bucket in the Pool but be sure to tie it to something, so it doesn’t float away! Mark the inside and outside water levels and leave for 24-hrs. Do this test once with the Pump running and once with the Pump off. If the level of water drops greater on the outside than inside, then you most likely have a leak.

Comparing the results

Comparing the results of the Bucket Test with the Pump on and off can provide additional information on the leaks location.

Water loss with Pump on > water loss with Pump off = suspect Return plumbing leaks (pressure side plumbing)

Water loss with Pump on < water loss with Pump off = suspect Skimmer/Main Drain plumbing leaks (suction side plumbing)

Water loss with Pump on = water loss with Pump off = suspect shell, liner or fitting leaks (non-plumbing)

If you would like to calculate the amount of water lost from your Pool in Gallons, see our Calculating water loss in Gallons page.

If you have no luck in the above tests or simply don’t have the time, contact us and we will be happy to help.