My water bills were too high so I checked my meter and found that the leak detection dial was spinning (ever so slowly - in fact it was more like it would be still...then build up enough to spin a tiny bit, and then repeat). I do not know where the main water shutoff to the house is, but I tried turning the water off at the water heater and BOOM the leak stopped. So that told me it was either in the hot water pipes or the radiant floor heating system (which covers a good 80% of the house). Now the floor heating system is typically a closed system, unless it needs to pull additional water in (if the system is drained for maintenance, etc). I called the company that installed the floor heating system because the plumbing in the water heating closet is super complicated. They supposedly isolated the system from allowing any water in (turning it into a closed system basically) and the meter continued to run. This tells me it isn't the floor heating. I should also mention that there is absolutely NO signs of any water in the house anywhere, with the exception of a musty smell in one bathroom...more on that later... I deduced that it must be in the hot water plumbing somewhere. The problem is that my house has been pieced together over the years and has a combination of slab foundation, a 'crawl' space, that is really about 10" deep (groan), and about five different roof lines, two of which are not accessible. My problem now is that I don't know where the plumbing lines run for the 10" deep crawl space side of the house. I have already cut two holes in the floor and three holes in the wall to trace pipes from various sources, but no moisture anywhere. I can see about 1/2 of the hot water pipes under the bathroom mentioned above, but again, no moisture whatsoever. I am going insane. Sorry for the rant. I have two questions: 1) Is there any way that I can confirm my hypothesis that the leak is in my hot water plumbing. I dont want to waste my time looking if I can rule it out. 2) Is there anything obvious that maybe I am not thinking of? The water heater is BRAND new (replaced after I initially found the leak, but the leak continues). I have checked my faucets for drips and see nothing odd.