Minerals in your water settle to the bottom of the tank as sediment. Over time that layer makes the heater rumble, run out of hot water sooner, and wear out early. Flushing washes it out, and it’s one of the most skipped jobs in home maintenance.

The Quick Answer

Once a year for most tank water heaters, and about every six months if you have hard water. That’s the schedule Rheem, one of the largest water heater makers, recommends.

Signs Your Tank Needs Flushing

• Rumbling or popping when the heater kicks on
• Hot water that runs out sooner than it used to
• A rusty tint in the hot water

Before You Flush

• Check the type. This is for tank heaters, gas or electric. Tankless units are descaled with a cleaning solution instead, following the maker’s instructions.
• Check the age. If the tank is 8 to 12 years old or more and has never been flushed, call a plumber first.
• Check for leaks. If the tank body leaks, don’t flush it. Call a plumber.

The Order That Matters

Shut off the gas control or the breaker before you drain. Let the water cool before you touch it. And on an electric heater, fill the tank completely before you turn the breaker back on. A heating element that comes on in an empty tank can burn out.

An Easy Monthly Habit

Between flushes, you can drain a few quarts from the drain valve into a bucket once a month. It takes about five minutes, carries off fresh sediment, and makes the yearly flush easier. Careful, that water is hot.

Keep Track

Write the date of each flush on a strip of masking tape on the tank. The next time you wonder whether you’re due, the answer is right there.

If you ever smell gas near the heater, leave the house and call from outside.

My guide walks you through flushing your water heater, step by step.

Get the full guide: How to Flush a Water Heater by Hank Palmer, on Amazon