It's a good idea to drain a water heater tank once a year. This removes sediment collecting in the tank, which comes in the form of naturally occurring minerals found in the water, along with sand and grit flushed from the municipal water supply. Over time, sediment degrades the heater's energy efficiency and performance and will clog valves and drains. Left uncleared, sediment leads to the appliance's premature failure.
Step 1: Cut Power and Water Supply
If you have an electric-powered water heater, shut off the power at the circuit breaker box. Most electric water heaters have their own breaker. Its important to note that electric heating elements will burn out if left active when the water level has dropped below them.
For a gas-powered water heater, locate the thermostat and turn the setting to "pilot."
Next, find the cold water supply line connected to the top of the tank and close the valve so water is no longer feeding into the tank.
Caution: the water in the tank will stay hot for several hours with the potential to cause injury even after you have shut off the power. Allow time for the water to cool.
Step 2: Connect Drainage Hose
Locate the drain valve near the bottom of the tank. Some models will have a cover over the valve that you need to remove.
Connect a standard garden hose to the valve and tighten.
If your water heater is above ground, like a first-floor utility closet or garage, run the garden hose outdoors to a place where the water can drain safely.
If the heater is in a basement, lead the hose to a floor drain if one exists. Otherwise, you will need to connect to a portable pump. Attach a second hose to the pump and run it outdoors to an ideal drainage area.
Step 3: Open the Hot Water Taps
Now you need to release the water pressure by opening the hot water faucets around your home. This alleviates the suction in the pipes —much like taking your finger off the end of a liquid filled straw.
This is a great time for someone to take a long, hot shower. It will speed up the drainage process.
Step 4: Open the Drain Valve
Return to the water heater to begin the drainage by opening the drain valve. If you have connected a pump, as mentioned above, it's time to activate it.
Allow the tank to empty. Don't forget that the water is still hot.
Step 5: Finishing the Job
Once the tank is empty, turn off the hot water faucets. Now you can go ahead with flushing or other maintenance work.
When you are finished, close the drain valve and remove the hose. Replace the cap if there was one. Open the cold water supply valve you closed earlier to refill the tank. Watch the drain valve to make sure it's not leaking and tighten it as needed.
When the tank is full, you can restore the electricity or gas power. Take caution by not turning on the heater before the tank is full, as this might damage the heating elements. Check the manufacturer's documentation for more information.
If you have any problems during this process, don't hesitate to contact a licensed plumbing and heating professional.