So you might want to check with the particular city.Beyond detecting thermal leaks thermal imaging is used to find hot spots in electrical systems and areas where water leaks are present, but not visible.

I have the idea of building a xband radar kit that detects motion outside the house, and plays the sound of a German Sheppard inside the house. 

If it does, you have a leak.http://www.wikihow.com/Detect-Toilet-Leaks

Someone else mentioned on a thread here that they started putting these humidity detecting fan switches in their rental bathrooms.

I've read several articles on urban sprawl but none offered a concise way to detect it.

As many have stated on BP,  Ice makers in Fridges can be a problem as when they start leaking it is hard to see and detect before damage is done.  

I am a detective at a police department in the Dallas-Ft Worth area.

She is not an expert in detecting asbestos.

A private detective may have resources to find them. 

Some guys do a basic magnetometer scan (detects metal) and others can do more comprehensive ground penetrating radar (GPR).