leaking hot water tank

I had a plastic fitting crack. Fortunately it was discovered before any floor was damaged. It did take 3 trips to HD to get parts to repair.

Better ask what make of water heater, Atwood or Suburban?

I would agree with a loose or cracked fitting on the back of the heater (inside of the cupboard). Take some tissue or toilet paper and squeeze it t around each fitting until you find the damp or leaking one. I found that the toilet paper, just a couple of squares will show the moisture much quicker than a visual or finger check.
If all these areas are dry and the water is coming from the insulation around the tank, you may have a much bigger problem.

Ken

Loose connection or cracked fitting.

Bypass the water heater and disable it.. Had that very problem and did not fix it fast enough now I got more secondary damage (Took me too long to figure it out) New tank on my Atwood was less than 300 dollars and quite a bit of labor (Did it myself) it is fairly easy to replace the entire unit. tank is a lot more work. .

I guess I would start by drying up the water all ready there. Then hook your hose back up turn the water on look and see were the water is coming from. It sounds like a pipe or connection is either broken or loose, but really until you know where the water is coming from its hard to really help.