How to Clean a Water Heater

hot water heater in basement or utility room
  • 1-2 hours
  • Beginner
  • 20-50
What You'll Need
1 gallon of CLR cleaner
Masking tape
Water hose
Plastic bag

Gallons of water pass through a water heater everyday, depositing minerals that make cleaning it difficult. However, if you don't keep your water heater clean, it can cause numerous issues. Using a dependable calcium, lime, and rust cleaner, or CLR cleaner, can make cleaning it easier. This cleaner will eat away mineral deposits where you can’t get to. Once you’ve picked a good CLR cleaner, use the steps below to get started.

Step 1 - Disconnect the Water Inlet Pipe

First, turn off the electricity at the breaker box, and mask off the switch to prevent anyone from turning it on while you are cleaning your water heater. Then, disconnect the water inlet pipe.

Step 2 - Drain Some Water

Take a water hose and attach it to the drain valve. Run the hose end to a basin where you can collect hot water. Open the drain valve after unscrewing the water supply line, and allow sufficient time for the water to drain out of the heater into the basin. Once the water has drained, close the valve.

Step 3 - Pour in the Cleaner

Now, slowly pour one gallon of your selected CLR cleaner into the inlet pipe. Pour about one capful at a time, allowing it to enter the pipe without overflowing.

Step 4 - Wait for the Cleaner to Work

tool box next to a water heater

Allow five hours for the CLR cleaner to dissolve any mineral deposits it can neutralize. You can test for neutralization by placing a plastic bag over the inlet pipe and seeing if it inflates. If it does inflate, wait another hour to re-check. When the bag does not inflate, the CLR cleaner has been neutralized.

Step 5 - Rinse the Heater

Next, rinse the heater by reconnecting the inlet pipe, and open the valve. Make sure you allow water to run through the heater for several minutes to rinse it thoroughly before moving on to the next step.

Step 6 - Fill the Heater

After closing the drain valve, turn on a faucet to fill the water heater. You will see soapy water exiting the faucet. Allow the water to continue flowing from the faucet until the bubbles disappear.

Step 7 - Open All Hot Water

water heater

Flush all air from the building’s water lines by turning on every hot-water faucet. Allow the water to run for several minutes. You might see water gurgling out at first. Once the water is freely flowing, turn off all hot-water faucets. If you continue to see bubbles for several days, do not worry. The CLR cleaner has been neutralized and is diluted enough that it will not cause any harm.

Step 8 - Turn the Heater On

After checking to make sure all inlet and outlet connections are firmly secure, turn the breaker switch back on to restart the heater.

Step 9 - Perform Regular Maintenance

To avoid frequent cleaning, flush your tank on a monthly basis. Consider installing a water softener if your water is consistently full of minerals. If your water heater is more than seven years old, repeated cleaning may cause it to leak, requiring a replacement.