Pool Leak Detection

Swimming pool evaporation?


Depending on the season, region and climate, swimming pools lose varying amounts of water due to evaporation. But if you are topping up your pool more than once a week, there is probably a leak somewhere.


Clues that your pool is leaking


Finding any of these symptoms is your cue to call Stop-A-Leak Leak Detection to stop the waste

  • Air bubbles entering the pool at the inlet is an indication that there could be leaking pipes;
  • Paving or lawn surrounding the pool are sinking or lifting;
  • Soggy patches in the ground around the pool;
  • Appearance of cracks in the structure of the pool.


Air bubbles coming out of the pool inlets, means that your pump is not only pumping water, but also pumping air through the pipes. This is a problem because it causes poor water filtration, which can quickly lead to water purification problems.

Air building up inside the filter tank could also be hazardous, if air pressure becomes too much, it can rupture the tank or tank clamp, and harm people nearby.


If you see air coming out into your pool inlets, or you see air in the pump basket, it's time to take action! The air has to come from somewhere, and specifically somewhere BEFORE the Pump Impeller, air is being drawn into the pipe or pump. After the pump, the pipes are under Pressure and any hole will result in water leaking out, not air leaking in. Before the pump, the pipes are under Vacuum or Suction, and any hole in a pipe, fitting, valve or pump basket area, will suck air into the pipe/pump. Air that is pulled into the pump is then pushed into the filter and back to the pool inlet, under pressure.


Stop-A-Leak is a leader in finding swimming pool leaks and spa leaks, being able to quickly detect where the repair needs to take place.​

Try the Bucket Test

  1. Make sure your pool is at a normal level;
  2. Fill a 20 litre bucket with pool water to approximately 100mm from the top;
  3. Place the bucket on the first or second step of the pool. Ensure the bucket is immersed deep enough in the pool at least 250mm or about a third of the bucket;
  4. Mark the water level inside the bucket;
  5. Shut off the pump and mark the pool water level on the outside of the bucket;
  6. Resume normal pool pump operation;
  7. After 24 hours, compare the two water levels. If the pool water (outside mark) goes down more than the bucket's water level (inside mark), there is probably a leak. If levels are the same, only evaporation has occurred.


In case of rain, repeat the bucket test. Test is invalid after 24 hours.​

Typical evaporation

Water loss of approximately 5-10mm is most likely evaporation. The evaporation rate in your area will depend on humidity, sunlight intensity, barometric pressure, wind and the level of activity in the pool or spa. You will have a much better idea after the test.​

Some common reasons for air in the system which you can check:


Pump Lid is not tight enough, or Lid O-ring is missing or damaged.

Solution: Also very common, you've got to really tighten pump lids very tightly after opening or removing the lid. Sometimes all it needs an extra turn to make a full seal with the pump lid o-ring. Sometimes a way too loose o-ring falls off, and the lid is put back without noticing that the o-ring is missing, or the lid gets covered in dirt and it does not make a good seal. Check the o-ring for a good fit, and replace if it has dry-rot cracks in it. To maintain a good pump lid o-ring, twice per year remove the o-ring, clean with a rag, and lubricate (Teflon lube).


Threaded pipe fitting going into pump is sucking air.

Solution: If the pump runs without water, or heats up in other ways, this can shrink the threads of the fitting that is threaded into the pump. Bad angles or excessive vibration can also cause the threaded seal of the fitting coming into the pump to loosen over time. You can make a patch with pool putty that will last for several months at least (leave the pump running for 24 hours to let the putty set up). Or, the other option is to replace the loose (and often shrunken) fitting with new.


Full skimmer and/or pump baskets, or clogged impeller.

Solution: When the baskets are clogged, or the impeller is full of small bits, it causes the pump to work harder to satisfy it's 'thirst' for water. This creates greater vacuum pressure and starts to leak air from places that don't normally leak air - when baskets are clean. Check the basket and impeller for any clogging material.


Filter was just cleaned and is still purging air.

Solution: When the filter tank is opened and the filters are cleaned, or if the pump basket is opened and water runs out of the filter, it can take a few minutes or possibly up to an hour before all of the filter air is pushed through the filter and sent to the pool returns.​



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