Over time, sediment can build up in your hot water heater, degrading performance and greatly shortening its lifespan. Cleaning out your hot water heater is a fairly easy project. First, turn off the gas or electricity to your heater, hook a garden hose to the boiler drain and turn the cold water inlet valve on. Turn on a hot water faucet in your home. After the water drains, turn your cold water inlet valve back on. Keep the hot valves on and run water until it runs without any air before you turn on the electricity or gas.