Why Flush Your Water Heater (and How Often)

What flushing does

Minerals in hard water settle to the bottom of the tank as sediment. Over time that layer insulates the water from the burner, so the heater works harder, makes popping or rumbling noises, and wears out sooner. Flushing drains the sediment out of the tank.

How often

In hard-water areas like ours, many plumbers recommend flushing a tank water heater about once a year. Tankless units need a descaling flush on a similar schedule to keep the heat exchanger clean.

Signs you're overdue

• Popping, rumbling or crackling sounds while it heats
• Hot water running out sooner than it used to
• Cloudy or gritty hot water
• Error codes on a tankless unit

A word of caution on older tanks

If a tank has never been flushed and is many years old, a heavy sediment layer can clog the drain valve, and older valves can start leaking once they're opened. That's a good reason to have a plumber do the first flush and check the heater while they're there.

By Murrieta Valley Plumbing · Updated November 8, 2026