How often should I flush my water heater?

The right interval depends mainly on one thing: how hard the water is. On typical municipal water, once a year is the standard for a tank water heater. On hard water — lots of dissolved minerals — every six months is closer to right. It’s one of the highest-value maintenance jobs there is, and one of the most commonly skipped.

Why sediment is the enemy

Minerals in the water settle to the bottom of the tank as sediment. Over time that layer acts like insulation between the burner and the water, so the heater burns more fuel to do the same job. The symptoms are higher energy bills and slower recovery after running out of hot water. Left long enough, sediment causes popping or rumbling noises, corrodes the tank from the inside, and takes years off the unit’s life.

When to do it

• Annually on typical water; every 6 months on hard water.
• Sooner if the tank rumbles or pops — that’s sediment boiling.
• Before winter is a useful anchor: the heater works hardest in cold months.

A note on safety

The water coming out is scalding hot, so heat-resistant gloves and patience matter. On a gas heater, if relighting a pilot isn’t comfortable territory — or there’s any smell of gas — that’s a job for a plumber, not a YouTube afternoon.

An annual flush pairs naturally with a T&P (temperature & pressure relief) valve test and, on many tanks, an anode-rod check. Those three together are the core of keeping a tank alive to 12–15 years instead of dying at 8. (Note: tankless units don’t collect sediment the same way — they need periodic descaling instead of flushing.)