How do you properly flush a water heater tank?

To properly flush a water heater tank, first turn off the power or gas supply to the heater. Next, connect a garden hose to the drain valve at the bottom of the tank and run the other end to a drain or outside. Open the valve and let the water drain out completely. Once the tank is empty, close the valve and refill the tank. Finally, turn the power or gas supply back on and allow the tank to heat up.