How often should you flush your water heater?

Once a year, drain a few gallons out of your water heater until the water runs clear. That’s the flush, that’s the headline, and if you have hard water, make it every six months.

Now the part nobody tells you at the hardware store: the flush is only the most famous item on the water heater’s list, and probably not even the most important one. The full schedule is short. All of it together is maybe two hours a year.

• Flush the tank: once a year (every six months with hard water)
• Test the temperature and pressure relief valve: once a year
• Look it over for leaks and rust: every six months
• Check the anode rod: every three years (yearly if you have a water softener)
• Professional inspection: once a year

What the flush actually does

Every gallon of water that enters the tank carries dissolved minerals, and when the water heats, some of them fall out of solution and settle. Year after year, a layer of sediment builds on the tank floor, right where a gas burner does its work. The burner ends up heating rock before it heats water. Your recovery time gets longer, your gas bill creeps up, and if you hear popping or rumbling from the tank, that’s water percolating up through the sediment layer, which is the tank telling you the flush is overdue.

Hard water builds that layer roughly twice as fast, which is where the six-month interval comes from.

The five-minute test that’s actually about safety

The temperature and pressure relief valve is the tank’s last line of defense against overpressure. Once a year, put a bucket under the discharge pipe and lift the test lever. Water should rush out, then stop cleanly when you release. If nothing comes out, or it won’t stop dripping afterward, the valve needs replacing. This is a serious one: a tank with a stuck relief valve and a runaway thermostat is a genuine hazard. The test costs five minutes.

While you’re down there each spring and fall, run a flashlight around the fittings and the base. Rust streaks, white crust, or dampness on the floor are all early warnings, and early is the only good time to hear them.

The anode rod, or why tanks die

Here’s the piece that decides your tank’s lifespan. Inside the tank hangs a metal rod whose whole job is to corrode instead of the tank. It’s called a sacrificial anode, and the name is literal: the rod dissolves over the years so the steel around it doesn’t.

Check it every three years. If it’s eaten down to the steel core wire, a replacement costs a small fraction of a new water heater and buys the tank years. One wrinkle worth knowing: a water softener, kind as it is to your fixtures, eats anode rods noticeably faster. Softened-water homes should check yearly.

The honest math

A tank water heater averages about eleven years. Looked after, fifteen is common. Ignored, eight, and the failure mode is rarely polite: tanks tend to announce retirement by putting forty gallons on your floor.

None of the jobs above are hard. The only hard part is that they’re spread across different intervals (six months, a year, three years) and no one remembers a three-year task. That’s not a character flaw. It’s what schedules are for.