Pools tend to leak in certain ways and in certain places and this information is used by leak detection specialists to find pool leaks. The testing process can get you close to the leak location but it is the experience of the person looking for the leak that is most helpful to help interpret the results of the tests properly. If you are a pool owner then you do not have the benefit of years and years of working on swimming pools. Without this experience it makes it harder for you to find leaks in your pool, but not impossible. Here are some of the most common and well known pool leak locations:
Return Pipes - The return lines for pools are a very common leak location. If the pool and the pool return pipes move (settle) in the ground at differing rates this will almost always result in a leak where the return meets the pool wall. This can often be heard with a stethoscope or even just by ear when the line is put under pressure. While breaks, cracks, or collapses in the pipe can happen anywhere, they are most likely to be where joint connections have been made.
Skimmer Pipe - The skimmer line for pools is a known leak point where the pipe connects to the underside of the skimmer. This is inherently a more difficult connection to make than a horizontal pipe connection. Also many skimmers are (and have been) made with ABS material, not PVC, and the transition between PVC pipe and ABS skimmer ports can fail. The underside of a pool skimmer is not conveniently located for service even in the best of circumstances. Concrete pool skimmers are also usually encased in concrete on all sides making the skimmer connection point even harder to get to. Even moderate pool renovations can skip skimmers for this reason so the skimmer on your pool may very well be original to the pool construction.
Skimmer Throat - The point where your skimmer throat connects to the wall of the pool is a well known leak location for all kinds of pools. With a vinyl pool you would likely notice rust staining where the skimmer meets the wall, but a concrete pool is more difficult to spot leaks. Dye testing around the skimmer connection point is one of the best solutions to finding leaks in these locations.
Main Drain - The main drain is also located in an unserviceable location on your pool. This means the main drain line on your pool can be older than other parts of your pool if yours has been renovated. Main drains can leak around the fixture itself, as well as through the suction pipe that connects to them. In addition to this main drains can develop leaks if the hydrostatic relief valve in them fails from rust, or from a rock obstructing the valve from closing properly. Dye testing, pressure testing and visual inspection all require a diver, or to drain the pool to inspect. Since you should not drain a pool this makes leaks in the main drain one of the hardest complicating factors for finding leaks in pools in general. If a pool does not have a main drain then it is much easier to isolate the plumbing system from the pool structure.
Equaliser Line - The equaliser line in the pool is a non pressurised pipe that connects from the main drain to the underside of the skimmer. This would allow water to access the skimmer even if the water level in the pool slipped below the mouth of the skimmer. This pipe is almost always left, even after a major renovation, so leaks in equaliser pipes are one of the most likely suspects with older swimming pools. Plugging the equaliser in the skimmer, and also on the other end in the main drain, can resolve a leak in this location.
Pool Lights - Pool lights are by far one of the worst offending leak causes in swimming pools. The electrical pipe where it connects to the light niche is a known leak problem, as is the electrical pipe itself. These components can be easily broken during installation of the pool or the backfilling stage. Leaks can also develop around the flange or fixture which dye testing can usually identify.
Structure Leaks - Structure leaks in a pool can happen anywhere. If you see a crack in a concrete or fiberglass pool then this would be the obvious first place to investigate if you are losing water. All types of pools can leak around any of the fixtures such as returns, lights and skimmers so if you suspect a structure leak scrutinize these areas the most closely. A vinyl liner pool can develop a leak anywhere it is punctured. This is commonly near where the wall meets the floor, and in the corners of the pool. When you look for holes in a vinyl liner pool you are looking for small half moon shaped imperfections in the vinyl.
If you want to find the leak in your pool then you need to follow a process of elimination style of tests to help lead you down the right path. Knowing how pools tend to leak is important but not enough on its own. While there are some leak detection processes which are not suitable for the average pool owner to do, such as pressure testing, most of the pool leak detection process is small, easily completed steps that anyone can do.
