Dan,

Are you talking about possible a leak below the slab?

If so, you should tell your customer they need to call a Plumbing contractor who specializes in such detection. They have specialized equipment which sounds out exactly where the leak is.

I had a customer years ago that was a termite client. I had went back one year because they had a reinfestation. I had taken off my shoes are getting a little mud on them from walking around the house. When I went treking down a hallway all of a sudden I could feel warmth below my feet.

Anywho, they call out this company and they said they'd be right out. I decided to hang around to check this out. They had some equipment that I was able to listen too with some headphones that you could actually pinpoint where the actual leak was happening.

She agreed to let them do the repairs. After an hour, they had jack hammered out a hole in the slab directly over the leak and had it fixed. The flooring was a mess, but the leak was history. A tree root had actually pushed against a copper line and pushed a solder joint apart.

Sometimes you have to call out the pro's.

Rick