During the spring, summer & fall, I host at state park campgrounds. My campsite & electric is comp'd, so I leave it (and my refrig. on electric) all the time. At my winter seasonal site, my electric is billed separately, so I turn it off at night - back on in the morning. I've found that the water stays warm enough over night to was hands etc. I'd like to think that saves a little $$, but can't be sure.