How to Clean the Inside of a Hot Water Heater

Don't attempt to clean out your water heater without a garden hose.

Cleaning the inside of your water heater can extend the life of your water heater, stop water heater noise and lower the cost of heating your water. Sediment from hard water and lime scale can build up inside your tank, clogging water pipes and eventually coating the surface of the heating elements in an electric water heater. If you have difficulty removing all the lime and scale buildup, consider hiring a plumber to professionally descale the tank with a phosphoric acid--based chemical delimer.

Things You'll Need

• Masking tape
• Tongue-and-groove pliers
• Heavy-duty garden hose
• Heavy-wire coat hanger or heavy-gauge wire
• Thread seal tape

Instructions

1. Turn the water temperature dial on the front of the gas control valve to the lowest setting, and turn the pilot control knob to "Off." Turn off the main gas supply valve that feeds gas to the control valve by turning the handle clockwise to shut off a gas water heater. Turn off the 30-amp double-pole breaker inside the main circuit breaker panel to shut off an electrical water heater.

2. Shut off the water supply valve to the water tank. Find the valve handle on the water line between the wall and the tank and turn it clockwise.

3. Remove the aerators from the faucets inside your home. Wrap masking tape around the teeth of a pair of tongue-and-groove pliers so you don't damage your faucets. Grab the aerators with the protected pliers and twist them counterclockwise.

4. Route the end of a heavy-duty garden hose outside your residence or over a floor drain. Twist the other end of the hose onto the drain valve located near the bottom of the water tank.

5. Turn on the hot water faucets inside your home to release air pressure inside your water tank. Open the drain valve by turning it clockwise to drain the tank. Close the drain valve and turn on the water supply valve, and let the tank fill for about 10 minutes. Turn off the water supply and open the drain valve. Observe the water that is flowing from the end of the garden hose. Repeat filling and draining the tank until the water runs clear.

6. Close the drain valve and remove the garden hose. Use the pliers to twist the drain valve counterclockwise to remove it from the water tank.

7. Straighten a heavy-wire coat hanger or use a piece of heavy-gauge wire to insert inside the drain valve opening on the water heater. Insert the wire into the water heater and scrape the bottom of the tank to loosen any scale.

8. Reinsert the valve inside the water tank and reattach the garden hose. Turn on the water supply for about 10 minutes, then drain the tank again. Repeat the scraping, filling and draining process until sediment no longer flows from the water hose.

9. Wrap the threads on your drain valve in thread seal tape. Clean around the opening on the tank. Close the drain valve and insert it into the tank, turning it clockwise until it's tight.

10. Turn on the water supply and fill the water tank. The tank is full when water flows freely from all the hot water faucets in your home. You may see sediment flow from the faucet and into the sink; this is normal, and is the reason you removed the aerators. Turn off the hot water faucets and replace the aerators.

11. Turn on the electric water heater at the main circuit breaker panel by turning on the 30-amp double-pole breaker. Turn the main gas supply valve on to supply gas to the control valve. Follow the directions printed on the side of your gas water tank to turn on the gas water heater.

References

• InspectAPedia: How to Flush Scale & Debris From a Hot Water Heater - Water Heater Tank Lime & Scale Removal
• Water-Heater-Repair-Guide: Flush Hot Water Heater
• Water-Heater-Repair-Guide: Drain Water Heater
• InspectAPedia: Hot Water Heater Tank or Electrode Lime & Scale Removal Procedure