How to Clean a Hot Water Heater With CLR

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Things You'll Need

  • Hose

  • Basin

  • CLR cleaner


If you see soapsuds in your hot water for several days following this process, do not be alarmed. The CLR is neutralized and very diluted at this point, so it should not cause any harm.

Flush your water heater monthly to prevent the need to clean it. You may also want to install a water softener to reduce mineral deposits.


If your water heater is more than seven years old, cleaning it may cause it to leak so badly that it must be replaced. Consider this before cleaning your heater.

Gallons of water pour through a water heater every day, leaving mineral deposits behind. Cleaning your hot water heater can be tough, but CLR cleaner can make it easier. CLR stands for calcium, lime, and rust. These three substances build up over time on surfaces that come into contact with water. CLR cleaner is a great way to clean your water heater, because it eats away at the minerals at the bottom of the heater without scrubbing. Although CLR often comes in small spray bottles, it is also sold in gallon-sized containers, the perfect size for cleaning a hot water heater.


Step 1

Turn off the water heater and disconnect it from the inlet pipe.

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Step 2

Attach a hose to the drain valve. Keeping the hose as straight as possible, put the other end of the hose over a basin or another area that will not be damaged by hot water.


Step 3

Open the drain valve and unscrew the pipe that supplies water to the heater. The water should drain out of the heater and into the basin. After it drains, close the drain valve.

Step 4

Slowly pour a gallon of CLR into the inlet pipe. Wait a few seconds after pouring each cupful so that it will all enter the pipe.


Step 5

Wait five hours for the CLR to dissolve the mineral deposits and become neutralized. Pinch the open end of a plastic bag over the inlet pipe and watch to see if it slowly inflates. If it does, wait another hour and test it again. If it doesn't, the CLR has been neutralized.

Step 6

Reconnect the heater to the inlet pipe and open the valve. Allow the water to run through the heater for several minutes to rinse it.


Step 7

Close the drain valve and turn on a nearby hot water faucet. This will fill the water heater, and soapy water will begin to flow from the faucet. Continue until the water flowing from the faucet is free of bubbles.

Step 8

Open the rest of the hot water faucets in the building to replace the air in the pipes with water.

Step 9

Turn on the hot water heater.