Through conversations with the pool owner and observations of the pool, confirm that the leak symptom being observed is indeed the result of a leak. A "Bucket Test" can be performed to determine how much of the observed water loss is due to evaporation and how much is due to a leak. Other tests such as the "Pump On/Pump Off Test" will provide a useful base of information that will be helpful as you continue the leak detection process.
2. Pressure Test Plumbing Lines:
Regardless of the suspected location of the leak, a pressure test of all plumbing lines will be done to confirm whether they do or do not have a leak. Plugging all but one of the openings in the pipe to be tested with assorted Closed Test Plugs. We set up a Pressure Induction System at the remaining opening. Useing water pressure from a garden hose to bring the plugged plumbing system up to around 20 psi. Closing the valves on the Pressure Tester and see if the pressure drops, which indicates a leak. If all plumbing lines hold pressure, water may be leaking through a crack in pool structure, tile or skimmer.
3. Pin Point Underground Plumbing Leaks by Sonic Leak Detection:
By using a air source to induce air into the leaking line a noise is created underground as air escapes into water saturated soil. Useing a Listening Device to listen through the earth for sound, the noise is then found and the leak is pin pointed. An estimate at that point can be prepared for the repair of the broken pipe.