Is there a dowser in your area? You may have another name for the people who use a forked stick to locate water. I have used one before. He could not locate a leak but only did part of the Community. I’ll probably have him back again. He did locate pipes and that helped a lot. He said it is not uncommon to have a really large leak that doesn’t come to the surface depending on your geology.
Northeasterner is right about getting off easy. The local health department, had they found out, could have made your life very difficult. That’s another reason to be nice to the residents and give them some sort of compensation.