Water heaters are the second largest source of energy consumption in your home. To maximize the efficiency of your water heater, limit the amount of time you spend in the shower. A long shower can use more hot water than a bath, even in a jetted tub. Keep the bathroom door closed tightly to increase the air temperature and make sure to run the exhaust fan to reduce moisture in the room.
You can also save money by lowering the temperature setting on your water heater. For every 10 degrees in reduction in temperature, you can save 3-5% on your water heating costs.