I was just remembering when we were building our house, we made a small bathroom and hooked it up to our septic system (it was nice to not use the bucket and have a shower at the end of the day). Our water was a 300 gal. tank up on the hill. For hot water we had a 100ft. of black hose loosely coiled up in the sun just outside the bath. This provided enough hot water for a couple quick showers until late Nov. (Of course the sun had to be shining and yes it would get hot enough to burn you unless you tempered the hot water)). You might keep this in mind if energy become a problem, black hose is a cheap and easy source of hot water.