the drain has a hand valve on the tank, and all I need to do is attach a hose... my house is an old frame structure 2' off the ground on pilings... the hose was originally made to flush the sand from the bottom of the tank, and drain out the door, which is a short distance, so I have the ability to completely drain the tank if necessary... the tank holds 50 gallons, so there should be a usable volume of water above the level of the valve even if I could not drain it completely ...I have stored water and an on site shallow well and filtering capacity...I don't ever perceive a need to use the heater as a source, but just wanted to throw out the idea incase anyone else might not have thought of it...regards