Pool Care /
How to Find a Leak in an Inground Pool
Start with a safe water-level check, then narrow the leak to evaporation, the shell, fittings, skimmer, or plumbing. Simple observations can guide next steps.
Archive date: this article was written for PoolSkimmer on Oct 24, 2026 and given the earlier archive date of Dec 11, 2025 so the blog reads as an organized archive. It was not published on that date.
Locating a leak in an inground pool
The first order of business is to be sure the pool is actually losing water and not simply evaporating. From there, put in some time to look over the shell, skimmer, any exposed plumbing and equipment for signs of trouble. You are not expected to do the repairs; the idea is to have some notion of where the problem lies before making a call to a pool pro.
Is it a leak or evaporation? You will usually see a leak as a more consistent and rapid loss of water than normal evaporation would account for. Some telltale signs are:
- The water level ceases to drop at roughly the same point
- Patches of dampness on the soil or deck, or wet spots by the equipment
- A pump basket full of air or one that will not hold its prime
- Any cracks you can see, loose fittings or drips
Do not make assumptions. Between backwashing, splash-out and general use, a pool will shed some water. Put it under observation for a while to be certain.
A safe approach to detection There is a logical way to go about this so an obvious leak does not get missed:
1. Put a mark on the water level and check back in 24 hours. 2. Examine the liner and shell for tears, separated seams or cracks. 3. Go around the skimmer, returns, lights and steps to see if there is staining or moisture. 4. See if the pump, filter, valves and exposed piping are weeping. 5. Note any change in the rate of water loss with the pump running or after a rain.
This will give you an indication of whether the issue is with the vessel, a fitting or the plumbing.
Where to look Leaks have a way of appearing in the parts of the structure that move or seal up. Be on the lookout at the skimmer throats, return lines, light niches, the bottom of the pool near a crack, and the equipment pad. If the water seems to settle at a particular height, the leak is probably at a fitting or opening at that level. Should it continue to fall below the skimmer, you may be dealing with something in the plumbing or a lower part of the structure.
The use of dye If you have a spot in mind, dye can be of assistance. Turn the pump off and put some food coloring in the vicinity of a seam or crack to see if it gets pulled into the opening. But consider it a clue rather than hard evidence. It is of no use if you cannot get a clear view or if the water is moving too much.
Pitfalls to steer clear of It is easy to make the task more difficult by assuming all water loss is from evaporation, or by trying to make chemical adjustments in lieu of a proper inspection. Do not reach into suction outlets or operate suction gear. And never work on the skimmer basket with the pump on; shut it down and follow the manual. Wear the appropriate PPE when you are dealing with wet equipment or debris.
Time to bring in a professional If the source remains elusive after a thorough visual, or if the water loss is considerable, put in a call to a qualified technician. The same goes for any movement or cracking in the deck. Most homeowners should leave pressure testing of the plumbing to the pros.
Make sure to stop and get help if you notice electrical issues or damaged gear. Under those circumstances, or if the water level is unsafe, do not swim.
In the meantime, keep up with the filtration system as the manufacturer intends but do not fiddle with the equipment unless you are sure it is safe. Make note of what you have observed regarding the water level and the likely location of the leak; having those details on hand will allow the technician to put the matter right more quickly.
Sources and further reading
- [Hayward: Weekly pool maintenance](https://www.hayward.com/maintenance/weekly-pool-maintenance)
- [Pentair U-3 skimmer manual: suction safety warnings](https://www.pentair.com/content/dam/extranet/nam/pentair-pool/pool-manuals/u-3-skimmers/395010028C.pdf)
- [SwimmingPool.com: Cleaning the skimmer basket](https://www.swimmingpool.com/maintenance/pump&filter/cleaning-the-skimmer&pump-basket)
- [CDC: Use pool chemicals safely](https://www.cdc.gov/healthy-swimming/media/pdfs/Pool-Chemical-Safety-USE-poster-p.pdf)
- [CPSC: Electrical safety in and around pools](https://www.cpsc.gov/safety-education/safety-guides/pools-and-spas/dont-swim-shocks-electrical-safety-and-around-pools)