Questions ?

How can I find water pipe leaks under concrete ?

If pipes were not embedded too deep under the concrete, you will notice some wet areas or ponding (like small ponds) on the concrete where leaks are suspected to be coming from However if the pipes are located on top of slopes chances are leaking water from the pipes may run down to the lowest portion of the slope and away from the real actual source of the leak another wild idea is to introduce a pressurized colored water thru the pipes. But you need to plug the outlet point before introducing a pressurized colored water to the entry point of the pipe and pressure must be increased gradually as if you are opening slowly a faucet from its closed lever position to its fully opened lever position but not sure if any colored dye can do the job for this finally the most expensive way but I think the most effective one is to excavate the pipeline suspected to be leaking