Install a Recirculation Pump
The California Energy Commission estimates that homes waste five to 20 gallons of water every day waiting for hot water to come out of the faucet.
If you’re one of those people who will run water until it gets hot, consider installing a recirculation pump. The pump has a thermostatically controlled sensor valve and timer and allows the hot water in the hot water supply line to constantly remain hot, so that the moment you turn on the shower, you’ll actually have hot water.
Over the course of a year, a recirculation pump might save you 1,825 gallons or as much as 7,300 gallons a year.
How much are they? The price varies, of course. You could spend several hundred dollars, but there are some good models out there for approximately $200.