It takes lots of energy to get water into your home--the aqueduct above uses 3,200 kilowatt hours to move an acre-foot of water (about 326,000 gallons) from Northern California to Southern California, or about 9.8 watt-hours per gallon. Once there, it takes energy to get it hot. Result: The California Energy Commission recently calculated that if they canceled a proposed energy efficiency program, and replaced it with a water savings program, they could save 95 percent of the energy for only 58 percent of the cost. So save your electricity bill and the planet: Lather quick.