Different brands and models of water heaters have different life expectancies and are rated by manufacturers for the number of years the consumer can anticipate they will last--for example, 6, 9, or 12 years. Regardless of its expected lifetime, your water heater requires periodic maintenance to continue operating at peak performance. The basic processes involved in a conventional hot water heater's operation are fairly simple. Cold water enters the bottom of the tank where a gas burner or electrical element begins to heat it. The warmed water migrates upwards, with the hottest water being at the top of the tank to a pipe from which it flows to the various faucets in your home. Over time, the minerals in the incoming water supply will precipitate and drop to the bottom of the tank, collecting in an insulating layer that seriously cuts the efficiency of the burner or heating element. Additionally, the flow of incoming water can stir up the sediment and send it through your home's water system where it can plug tap aerators, shower heads, and washing machine filters. Flushing these mineral deposits out once a year is essential maintenance and easy with the following steps.

Temporarily disable the gas burner or electrical heating element. Depending on your hot water heater, you may find a pilot switch that kills the flame and gas supply in one step. Put safety first:  read and follow the manufacturer's directions to ensure that you don'leave a gas valve open while you work. If your water heater is electric, it may have a disconnect switch at the tank or you may need to go to the breaker box and switch off the electrical circuit which feeds it.

Shut off the cold water supply to the tank, turning the cut off valve to the full "off" position. You want to drain the tank completely without having an incoming flow of water competing with the emptying process.

Open the valve and let the water flow out the garden hose. On completion, Remove the hose, close the exit valve, restart the cold water supply, and shut off the hot water faucets elsewhere in the house where you opened them. Restart the heat source, following manufacturer's directions for your hot water heater. Most modern hot water heaters have a piezoelectric igniter and a simple button to push that makes a spark to light the gas. Today, not many require a match to light a pilot. If your tank is electric, restart it at the tank if you have a disconnect/reconnect switch--otherwise, return to the breaker box and flip the switch on the correct electrical circuit for the hot water heater.