By Ann Edminster Water heating accounts for nearly one-fifth of home energy use. When you open the hot water valve, you’re saying “come hither” to hot water in the tank … and yet in the amount of time, for hand-washing to take place, it’s unlikely that hot water will actually arrive at the tap. Both the Centers for Disease Control (CDC) and Mayo Clinic instruct to wash hands in either cold or warm water. Hot water does not make for cleaner hands and it’s harder on the skin! If you use a single-handle faucet, be aware they are phantom energy wasters. When the handle is in any position except fully cold, it opens the hot water valve and wastes energy.