Turn off the water heater power or gas supply
Turn off the cold water inlet valve
Let the water cool if needed
Connect a garden 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 on the water heater
Drain the tank completely
Briefly open the cold water supply to stir up sediment if needed
Repeat draining until water runs clear
Close the drain valve
Remove the hose
Close the hot water faucet
Refill the tank by opening the cold water inlet
Open hot water faucets until air stops flowing
Check for leaks
Restore power or relight the gas supply