It was mentioned earlier about pressurizing the interior to find leaks. This covered in some forums (maybe here), see this one for starters.
http://www.class-c-motorhome-info-made-simple.com/leak_test.html
The idea is to pressurize the coach with a fan, such as the diy used in this link. Every opening other than the air input opening, must be sealed with duct tape or similar. A water spray bottle (or brush) with a soap solution to check all suspect areas. Better directions are in the link, and others.
There are some dealerships and shops that will perform the check for a fee.
This looks to be by far the best and easiest to find water leaks in any type of RV. Good luck.
