Water Heater Maintenance 101

Performing basic maintenance tasks on your water heater can help ensure that it reaches its maximum life expectancy (typically 10 to 20 years, depending on the type and model).

water heater maintenance by contractor


Water heaters are major home appliance, and when they break or need to be replaced, it can be a significant expense (and a major pain). Performing basic maintenance tasks on your water heater can help ensure that it reaches its maximum life expectancy (typically 10 to 20 years, depending on the type and model). While there is typically no need for routine checks from a technician, performing your own upkeep, and knowing when to call a plumber, will help keep your unit running as it should, for as long as it should.

First Steps

Read the manual.

The "Use and Care" manual that comes with the water heater will spell out any maintenance requirements. If you don't have the manual, visit the manufacturer's website to see if you can order or even download a copy.

Know the type of unit and its shut-offs.

There are a few different types of water heaters, the most common of which being storage tank heaters and tankless heaters. Each type operates differently. Get familiar with the kind of water heater you have, and how to shut off the water and power to the unit before doing any maintenance tasks. If you have an electric water heater, look for a cutoff switch near the unit. If you don't have one, locate the circuit breaker in the electrical panel box that controls the water heater. For gas water heaters, close the valve on the gas line that connects to the heater. To shut off the water on any type of water heater, close the valve on the cold-water line near where the line enters the unit. If there is no valve, you will need to shut off the water at the main valve where the water line enters your house.

Heed safety warnings.

You will find that much of what can be called routine maintenance is just common sense. Pay attention to the warning stickers placed on the water heater. Gas heaters contain vents that must be kept clear so that the unit can operate properly. And store flammable items like paint thinner away from the water heater. In general, keep the area around the water heater free of clutter.

Tank Water Heater Maintenance

Removing Sediment.

All water contains sediment that over time can settle on the bottom of the water heater tank. If allowed to build up, it can interfere with the performance of the unit.

"If a gas heater percolates as it heats—you will hear it—suspect calcified minerals on the bottom of the tank," said Merle Henkenius, a licensed master plumber. "Drain the water and run new water through the tank to flush the bottom. Electric heaters will short out if covered by calcium flakes."

Follow the manufacturer's recommendations for how much water to drain and when to do it.

To drain an electric water heater, shut the unit down completely. You will be draining water from the tank, and if the heating element inside the tank should click on and it is not covered with water, it could be damaged. For gas heaters, set the control dial on "pilot." Turn off the cold water supply to the tank.

The easiest way to drain the tank is to connect a garden hose to the drain valve located near the bottom of the tank. Run the hose to a nearby drain. Open a nearby hot water faucet, and leave it open. Then open the drain valve. Caution: The water will be hot. Drain the tank until the water runs clear. This may take a few minutes or longer.

When finished, turn the water back on. You'll know the tank is full when water runs from the faucet you left open. When the tank is full, close the faucet and restore power to the water heater.

Testing the Temperature-Pressure Relief Valve.

The temperature-pressure relief valve does just what it says it does—it relieves the pressure that may build up in the tank. Test the valve at least once a year. Place a bucket on the floor under the extension tube. Caution: Stand back because hot water will be released from the valve. Lift the valve up so that it is parallel with the floor. There should be a release of pressure and water. Push the lever back into position to close the valve. If nothing happens, the valve may be defective. "The temperature-pressure release valve is the most valuable thing on the water heater. If water does not come out when you open it, you have a serious problem," said Henkenius. Consult a plumber.

Inspecting the Venting System.

On top of a gas water heater is a draft hood that is attached to connectors that run to a chimney. Check it periodically to make sure it is drawing properly. With the burner running (you may have to increase the water temperature setting to get the unit going) put your hand near the opening between the hood and the top of the tank. You should feel air from the room brush across your fingers and up the draft hood. You can also use a smoke stick or incense stick near the opening to determine if the flue is drawing. If the flue is not working properly, harmful gases could be going into the room rather than up the chimney. If you are unsure, call a professional plumber to inspect the system.

Replacing the Anode Rod.

Suspended inside the tank is a long metal rod made of aluminum, magnesium or zinc, or some combination of metals. Its sole purpose is to sacrifice itself for the sake of the lining of the water heater's tank. Anything that is corrosive in the water will attack the rod, not the walls of the tank. Eventually, the rod needs to be replaced. "You can double the life of the heater by replacing the rod near the end of the warranty period," said Henkenius.

To check the condition of the rod, turn off the power and the water. Open a hot water tap nearby, and leave it open. Drain off four or five gallons of water through the drain valve. This will help prevent water splashing up on you as you remove the rod. It is not necessary to drain the entire tank. If the rod looks corroded, it may be time for a replacement. For serious DIYers, it is possible to do this yourself—consult your manual. Others may opt for a plumber to perform this somewhat-involved maintenance task.

Tankless Water Heater Maintenance

Cleaning the Filter.

Tankless water heaters have a small filter near where the cold water inlet enters the system. The filter should be cleaned every few months or per the manufacturer's recommendations. Turn off power to the system and the water supply, and remove the heater's cover. The filter may be labeled. If it’s not, consult the "Use and Care" manual for its location. Generally, you simply remove the filter and rinse away any sediment under tap water. Reinstall the filter, and turn the water and power back on.

Dealing with Lime Scale.

To remove scale that can build up on components, tankless water heaters should be flushed with plain white vinegar. The job is much easier if service valves are installed at the cold water inlet and hot water outlet of the unit, because they allow you or a technician to isolate the unit from the house's water supply system. In many cases, these valves are sold as add-ons and do not come with the unit. Consult the manual or a plumber or assistance in flushing the unit.

Caring for your water heater properly can help extend its life and improve its performance. When in doubt about a routine task or a major repair, call a plumber. And when it does come time to find a new water heater, consult our water heater guide. 

Fran Donegan writes home- and garden-related content for numerous digital and print publications.  He is the author of the books Pools and Spas (Creative Homeowner Press) and Paint Your Home (Readers Digest). To learn more about water heaters like those referenced by Fran, please visit Home Depot's website.

AHS assumes no responsibility, and specifically disclaims all liability, for your use of any and all information contained herein.

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