Change in plans

So, I’m not going camping because I’m trying to figure out what to do about my just discovered leaking hot water heater. Right now I’m draining the semi-hot water but there doesn’t seem to be a bypass to turn the main water line off to just the tank. Dam it! I’m not a plumber and don’t want to be one. Also very far away from possible repairs. There goes having fun on my days off. Guess it could be worse and the roof could be leaking in a hard rain. But then I’d just throw a tarp over it. Hmmm. What to do?