to drain or not to drain fresh water

Drain every season and sanitize. Then whatever is inside is inside for the season and replenished as used. Use bottled drinking water and a pump on a 5 gallon sparklett's jug for cooking. I have not drained water heater specifically, but I do heat up the water when I exercise the generator. Right or wrong, it has worked for me from camper to Class C and now to Class A. I will add that there is this fluid called beer that comes in "Olympia" aluminum cans and another fluid called whisky that comes in glass containers with Jack Daniel's on the label that is used for drinking too:)

Check this out! Good timing...

http://thervgeeks.com/quick-tips/sanitize-rv-fresh-water-tank-without-winterizing-kit/