Turn off the power or gas supply to the water heater
Shut off the cold water supply valve
Let the water cool if needed
Attach a hose to the drain valve
Run the hose to a safe drain area
Open a hot water faucet in the house
Open the drain valve and empty the tank
Close the drain valve
Turn on the cold water supply briefly to flush sediment
Repeat flushing until the water runs clear
Close the hot water faucet
Remove the hose from the drain valve
Refill the tank completely
Check for leaks
Restore power or relight the pilot if applicable
Run hot water from a faucet to remove air from the system