This is the strangest tip I've ever shared on this forum. Please don't make fun of me. 
You know how long it takes to run hot water to the sink when all you want is a warm wash cloth? A waste of time and water. Then it dawned on me...use cold water to wet the wash cloth, wring it out, roll it up like a jelly roll and microwave for 25-30 seconds. Piping hot towel, no wasted water, and about 1/10 of 1¢ in electricity. Brilliant! This must be what they do on airplanes when they offer you a warm towel at the end of a long flight. (Remember flying?)
Of course, your microwave time will vary. Use care, the water can get really hot if you microwave too long.

You know how long it takes to run hot water to the sink when all you want is a warm wash cloth? A waste of time and water. Then it dawned on me...use cold water to wet the wash cloth, wring it out, roll it up like a jelly roll and microwave for 25-30 seconds. Piping hot towel, no wasted water, and about 1/10 of 1¢ in electricity. Brilliant! This must be what they do on airplanes when they offer you a warm towel at the end of a long flight. (Remember flying?)
Of course, your microwave time will vary. Use care, the water can get really hot if you microwave too long.