I never had my 2007 HWT out, but I have serviced it. One place of potential leakage/failure is the electric heating element. It has plastic that just might have cracked. If you are able to access yours like I am, it is at a low point close to the floor and faces towards the inside of the motorhome. I had to remove the access panel to get to it. If you decide to change it, first place as many towels as you can stuff because even with the HWT empty, 1/2 gallon of water still comes out, I assume to assure the element stays submerged even with an empty tank for protection from accidental turn-on during plug-in storage.
The electric heating element resembles this. Maybe it cracked and is leaking. As I recall, a new heating element was very affordable.
