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Water Heater Maintenance Checklist

Last updated October 15, 2026.

Safety first: If you smell gas, leave now and call the gas utility or 911 from outside. If a CO alarm sounds, get everyone outside and call 911. If hot water or steam is spraying from the heater or its relief pipe, stay back. For a serious burn, call 911.

Most water heater care is set by your owner’s manual. Here is what it asks for, what you can do yourself, and exactly why the rest is a plumber’s job.

Pick a time you’ll remember. Your manual sets how often.

Water hardness

Your water’s hardness changes how often some heaters need care, but the schedule comes from your owner’s manual, not from a hardness label alone. On city water, look up your utility’s yearly water quality report (often called a Consumer Confidence Report) and find “hardness.” It may be in grains per gallon (gpg) or in ppm or mg/L. On a well, or if the report doesn’t list it, use a hardness test strip from a hardware store, following the package directions. Soft, moderately hard, hard, and very hard are plain-language categories from the U.S. Geological Survey for describing water (TRADE). They are not a service schedule. If you have a water softener, some manuals ask for more frequent anode checks — follow your owner’s manual. For flush, descale, and anode timing, follow your owner’s manual.

Look around

Once in a while, look without touching: water on the floor or in the pan, drips from the relief pipe’s end, rust at the fittings or top of the tank, or new popping sounds. Outside, check that vents aren’t blocked. If you smell gas, leave the house now and call the gas utility or 911 from outside. If you see any of the other signs, start a guided check.

Relief valve

If your manual tells you to test the relief valve, we’ll walk you through it. If it doesn’t, leave the valve alone.

Start the guided check and choose Water heater.

Heat pump water heater filter

Heat pump water heaters have an air filter on top. Clean it when the filter light comes on, as your manual shows.

Tank flush

Sediment settles at the bottom of a tank, more so with hard water. Your manual asks for a yearly flush. We don’t guide this one: it means draining very hot water through a valve that can clog open, and on gas or electric tanks it means shutting off and restoring the heat source. Book a plumber to flush the tank.

Draining means hot water through a valve that sediment can jam open, and refilling before power or gas comes back. An electric element powered in an empty tank burns out, and a gas tank needs relighting. Those are plumber steps.

Anode rod

The anode rod is a metal rod that slowly wears away so the tank metal doesn’t. Your manual says how often to have it checked (for some models, every year). Checking it means taking it out of the tank, so we leave it to a plumber. Ask them how much core wire is showing. Your manual lists when it should be replaced. If a heat pump water heater shows an anode alarm, call a licensed plumber or water heater professional. Clearing that alarm is only for after the anode has been serviced or replaced, as your manual describes — otherwise leave it and call.

The rod is screwed tightly into the top of the tank and often seized. Removing it needs the gas or power and the water off, part of the tank drained, and a heavy wrench. Forcing it can damage the tank. A tank left without one rusts out faster.

Tankless descale

Hard water leaves scale inside a tankless heater. When your heater shows a service code for this, or your manual says it’s time, book a descale. The heater needs service valves on its water lines for this. If yours has none, a plumber can add them.

Descaling means closing and opening four valves in the right order and pumping a cleaning solution through the heater. A wrong valve sends the solution into your pipes or hot water at the heater. The maker calls it a complicated procedure.

Tankless inlet screen

Your tankless heater has a small screen where cold water comes in. If it clogs, you may get less hot water or an error code. Cleaning it means draining the heater, so book it with your descale.

The filter sits in the water line under pressure. Reaching it means shutting the water off and draining the heater. A pinched or missing seal leaks when the water comes back on.

Is this normal?

Popping or rumbling in a tank is often sediment. It’s common and not an emergency on its own. Not normal if you also see water at the base or a relief pipe that’s running — then call a licensed plumber or water heater professional. Don’t open the drain valve or try to drain or flush the tank yourself.

What a pro service visit should include

A water heater service visit should list what was done. For a tank: flush, anode checked against your manual’s replacement rule, relief valve checked, and for gas, the burner, venting and gas connections. For tankless: descale, inlet filter, venting, and the error history read (not cleared). For a heat pump model: filter, condensate drain and the system checked for alerts. Ask for the results in writing.

Independent information, not an inspection or a confirmed diagnosis. Not attorney-reviewed and not a licensed HVAC review. support@secondwrench.co