Nothing is more maddening to an in-ground swimming pool owner than to watch her pool's water level drop daily through some unseen leak. In-ground swimming pool basins develop leaks through various means, including tears in pool liners. Swimming pools, though, can also develop leaks elsewhere, including their hydrostatic valves and filter systems. Other likely sources of in-ground pool leaks include around fittings and skimmers. Finding a leak in an in-ground swimming pool takes a bit of detective work but it can be done.
The first place to check when it comes to a leak in a swimming pool is within its basin. Also, pool fittings and skimmer faceplates can develop leaks. A leak in a pool's basin is detected through use of simple dye test to track colored water making its way to the leak. If you suspect you have a leak coming from your pool's filter fittings or the skimmer perform a visual inspection for moisture or drips around such equipment.
Find underwater leaks in any type of in-ground swimming pool basin by using special dyes and syringes sold in pool supply stores. You can also make up a swimming pool leak detection kit by using dark food coloring and a turkey baster. Get as close to the site of a suspected pool basin leak as possible and then squirt dye, watching to see where it goes. If a pool basin has a leak, dye introduced near it will quickly exit through that leak.
An in-ground concrete or fiberglass swimming pool is typically fitted with a hydrostatic valve. Check under the pool's main drain cover for the hydrostatic valve and apply dye near the main drain to see where it goes. A hydrostatic valve helps equalize pressure between the water in a pool basin and the groundwater beneath it. Old, worn out hydrostatic valves are often the culprits when it comes to an in-ground swimming pool leak. Have your pool's hydrostatic valve replaced about every five years.
In-ground swimming pools have underground plumbing systems that are inaccessible to visual inspection or use of dyes to detect leaks. Consult a swimming pool leak professional if you suspect leaks in its underground plumbing. Also, if air bubbles are coming from your pool's water return ports there's a leak in your pool's return lines at some location along those lines. Lastly, other areas in a swimming pool that tend to leak are sharp corners or along any seams.