Depending on a homeowner's water quality in San Antonio, a hot water heater can be expected to last eight to 12 years, says Frank Czeronka, a licensed master plumber and Mr. Rooter franchise owner. Completing the following routine maintenance schedule, however, can greatly extend the unit's lifespan.

Here's a list of maintenance tips to keep your water heater running efficiently and reliably:

• Always adjust the thermostat to 120 degrees to avoid the risk of scalding.

• Always maintain 2 feet of clearance around the appliance unless the manual specifically states otherwise.

• Annually, flush the heater to remove the sediment and debris in the bottom of the tank. Hook up a garden hose to the drain valve and run until the water is clear. This also makes the unit operate more quietly.

• Annually, test the temperature-pressure relief valve by quickly discharging it two or three times. Following the testing, keep an eye out for small leaks from the valve.

• Every three to five years, examine the sacrificial anode rod by loosening the hex head screw and removing it. If more than six inches of the core steel wire is exposed, replace the rod for abut $20.

• Insulate older units with a fiberglass jacket to improve efficiency, being careful to avoid contact with the flue. Newer units already are optimized for peak energy efficiency.

• When leaving town, adjust the thermostat on gas heaters to "Vacation" setting, which maintains the pilot light without heating the water.