family smiling at kitchen table

How to Maintain a Water Heater

Purchasing a new water heater or replacing your current model can be expensive. Get the most out of your water heater by performing routine maintenance

Benefits of Preventative Hot Water Heater Maintenance

Save on Electricity

When your water heater operates at peak efficiency, it uses less energy, translating into lower electricity or fuel costs

Water Faucet Icon

Proper water heater care also removes sediment buildup and corrosion to improve the taste, feel, and overall quality of your water

Set of Plumbing Wrenches

Noticing and fixing minor issues with your unit can prevent big problems and save you money on repair and replacement costs

Safety Shield Icon

Preventative maintenance increases safety levels in your home by preventing electrical and gas issues

Content Links

How to Turn a Water Heater Off and On
How to Relight the Pilot
How to Check the Sacrificial Anode Rod
How to Drain the Tank
How to Flush the Tank
How to Adjust the Temperature
Insulating the Pipes and Unit
Handling Leaks and Drips

Safety First

With a little attention and maintenance, you can keep your gas and electric water heaters working efficiently. If you’re not comfortable working with gas or electricity when caring for your water heater, however, call a professional. 


Caution

Always wear gloves, goggles and other protective clothing while performing maintenance on your water heater.



Find A Local Installer


Shop A. O. Smith Water Heaters
Shop A. O. Smith Water Heater Parts & Accessories
Shop A. O. Smith Pressure Tanks
Download PDF Summary pdf-link

Water Heater Maintenance: The Components

The Temperature & Pressure Relief Valve

T&P Valve with Tag Attached

T&P Valve with Instruction Tag

Opening T&P Valve

Opening T&P Valve

Both gas and electric water heaters have a safety device called a temperature and pressure relief valve, or T&P valve for short.


In the event the tank is over-pressurized, the relief valve opens and releases the pressure. If the valve doesn't operate correctly, the tank can over-pressurize and explode.


Simply lift the lever to open and close the T&P valve a few times to make sure water is discharged from the tank. Inspect the Temperature and Pressure (T&P) relief valve per instructions on the valve’s label.


T&P relief valves will drip if the water pressure is too high or due to thermal expansion on a closed plumbing system. Control water pressure and install a thermal expansion tank before replacing a dripping T&P relief valve.


Find a local pro to help with this issue


The T&P valve should be inspected by once a year by the consumer and every 5 years by a professional.

The Anode Rod

Cutaway view of electric water heater

Water Heater Tank with New Anode Rod

Cutaway view of electric water heater

Anode Rod "Dissolves" to Protect the Tank

To help protect the tank from corrosion, a sacrificial anode rod made from aluminum, magnesium, or zinc is installed in all steel water heaters to attract damaging elements like minerals and salts that exist naturally in the water supply. In this way, they are "sacrificed" to protect the tank from corrosion.


How long an anode rod will last depends on what chemicals are in the water, how much hot water is used, and whether or not a water softener is installed. To extend the life of your water heater, we recommend inspecting the anode rod once a year.

Performing Water Heater Maintenance

Water main shutoff valve

Virtually every maintenance task you will perform will begin with turning off power to the water heater and turning off the flow of water to the heater. Follow these basic steps to turn off power to your unit.


Caution—Always wear gloves, goggles and other protective clothing while performing maintenance on your water heater.



Important—Make sure water heater is completely full of water before returning to service. Serious damage to the water heater or components can occur is the water heater is turned on without a full tank.


Ideally, you should turn your water heater off for a few hours before draining the tank. Turning the unit off beforehand allows the water to cool and reduces the risk of scalds. Always wear thick gloves and safety goggles to protect your skin while you drain the water heater. 


Be sure you know where the main water shutoff valve is if you are only turning off the supply to the water heater. Knowing how to stop water flowing into your plumbing system can help prevent floods if you make a mistake while draining your water heater.

Turning the Water Heater Off and On

Step 1 - Turn Off the Unit


Turn off the electricity to the water heater or turn off the gas to extinguish the pilot. Open a faucet to run the cold water.

Turn off power at breaker
Turn off at breaker
Set the pilot light to OFF

Set pilot to "Off"

Step 2: Find a Safe Place to Direct the Water


You'll need to direct the water into a safe place to avoid flooding your home.


Most homeowners use a large bucket to catch the water flowing from the drain valve.


Alternatively, you could direct the water down a drain if your hose can reach that far. It's also worth having old towels or rags on hand to soak up any spills.

Direct water into bucket
Water pipe to drain

Step 3 - Drain some or all water from the water heater.


Shut off the incoming cold water. Attach a garden hose to the drain valve.


Open the drain valve and let a few gallons of water drain from the water heater (when checking anode rod), or let all of the water drain out (when draining or flushing the tank).


You may need a flathead screwdriver in order to open the drain valve.

Closing plumbing valve to shut off water
Opening the drain valve

Step 4 - Turn the Unit Back On


Close the drain valve in order to fill the tank.


Open the input valve to let water into the tank. Refill the water heater, purge all the air from the tank by running a faucet for several minutes. Turn the power on or relight the pilot light, and check for leaks.


For an electric water heater, it is critical to make sure the tank is full before turning the power back on. If there is not enough hot water around the heating element, it will burn out and, and you’ll have no hot water until the upper element is replaced.

Turn water back on
Run water from the faucet
Return to Task List

Relighting the Pilot

With the gas valve knob set to pilot, press and hold in the knob and push the igniter button one time a second for up to 90 seconds. The light will blink when it’s lit and you should see a small flame through the view pane. Set the temperature to 120 degrees Fahrenheit.


Caution

Read and follow your manufacturer’s lighting instructions for more detailed instructions on lighting the pilot.

Pushing knob to light pilot
Lighting the pilot

Good to Know

Newer water heater models have a smaller pilot light, which may be hard to see. If so, darken the room and look carefully through the sight glass in order to see the pilot light.


A gas water heater may produce condensation the first time it is lit. You may hear dripping sounds or see a small puddle of water in the drain pan. This condensation is normal and goes away once the water heater reaches its normal operating temperature.

Return to Task List

Checking the Sacrificial Anode Rod

Sacrificial anode rods protect the inside of water heater tanks from a process called galvanic corrosion. Because water heater tanks are made from metal that’s susceptible to corrosive elements in water, the anode sacrifices itself to protect the tank. The anode freely gives up ions so electrolysis does not dissipate the steel of the tank.

Step 1 - Turn Off the Unit


Turn off the electricity to the water heater or turn off the gas to extinguish the pilot. Open a faucet to run the cold water.


Step 2 - Drain some water from the water heater.


Shut off the incoming cold water. Attach a garden hose to the drain valve. Open the drain valve and let a few gallons of water drain from the water heater. You may need a flathead screwdriver in order to open the drain valve. Close the drain valve to continue the process.

Run cold water from the faucet
Direct water into bucket

Step 3 - Locate and Remove the Rod


Locate the sacrificial anode rod. This water heater component typically hangs down into the tank from the top. Using an electric impact wrench, use a 1 1/16 deep well socket to remove the anode.


If the space above the water heater is limited, pull up a portion of the anode rod, cut it off, and repeat until the rod is removed.

Loosen the anode rod
Inspecting the anode rod

Step 4 - Inspect the Rod


Perform a visual inspection. A rod in good working condition should be smooth and around a half inch in diameter. If the sacrificial anode rod shows signs of deterioration or has several inches of exposed core wire, replace it.


Determine the type of sacrificial anode rod your water heater needs, typically magnesium, aluminum or zinc.

Stages of an anode rod
Types of anode rods

Step 5 - Install a New Rod If Necessary


Install the new part in place of the old one, making sure to properly align all parts and secure all threaded screws.


A segmented anode rod is an option for replacement in restrictive spaces.

Segmented anode rod

Explore our collection of A. O. Smith product literature to find the resources you need for your specific model.

Step 6 - Turn the Unit Back On


Open the valve to let water into the tank. Refill the water heater, purge all the air from the tank by running a faucet for several minutes. Turn the power on or relight the pilot light, and check for leaks.


For an electric water heater, it is critical to make sure the tank is full before turning the power back on. If there is not enough hot water around the heating element, it will short out and destroy the element.

Turn water back on
Run water from the faucet
Return to Task List

Draining the Tank

Knowing how to drain a hot water heater is also an important step if you are preparing to remove and replace your unit.

Ideally, you should turn your water heater off for a few hours before draining the tank to allow the water to cool and reduces the risk of scalds. Always wear thick gloves and safety goggles to protect your skin while you drain the water heater. 

Step 1 - Shut Off the Unit


Turn off an electric water heater by flipping the circuit breaker on your main breaker panel.


If you have a gas water heater, you can turn the unit off by moving the dial on your thermostat to the "OFF" position to extinguish the pilot light.

Turn off power at breaker
Turn off thermostat on gas water heater

Step 2 - Turn Off the Water Supply


Shut off the cold water inlet to the water heater. Open a faucet and run the water until it goes cold.


Connect a garden hose to the tank's drain valve. Place the hose’s draining end in an area that can handle several gallons of hot water.

Closing plumbing valve to shut off water
Run hot water from the faucet

Step 3: Find a Safe Place to Direct the Water


You'll need to direct the water into a safe place to avoid flooding your home.

Most homeowners use a large bucket to catch the water flowing from the drain valve.

Alternatively, you could direct the water down a drain if your hose can reach that far. It's also worth having old towels or rags on hand to soak up any spills.

Direct water into bucket
Water pipe to drain

Step 4: Connect a Hose to the Drain Valve


Attach your garden hose to the drain valve at the bottom of your water heater. Your user manual can help you locate the water heater drain valve if you can't find it.


Depending on the valve type, you may need to connect a threaded hose cap to ensure a watertight fit. Place the other end of your hose inside the bucket or exterior drain.

Attach hose to drain valve
Drain valve

Step 5: Turn on a Hot Water Tap in Your Home


Turn on a hot water faucet in your sink to prevent pressure from building up inside your plumbing system. If you've shut the water off correctly, the tap should release a gush of water followed by a slight trickle.


Close the water supply valve more tightly by turning it clockwise if the water continues flowing normally.

Hot water from faucet
Closing plumbing valve to shut off water

Step 6: Open the Drain Valve


Finally, open the water heater's drain valve to release water into the bucket. Most water heaters have manual-open drain valves, but you may require a flathead screwdriver if you can't open the valve by hand.


Water and sediment will flush through the hose and into your bucket or drain. If you're using a bucket, turn the drain valve off as your bucket fills and empty the water to prevent it from overflowing.

Attach a hose to the drain valve
Unscrewing the drain valve
Return to Task List

Flushing the Tank

Water heater flushing is an essential part of your home maintenance routine. Over time, minerals and other substances in your water supply can cause sediment buildup inside your unit, increasing the risk of leaks, bad smells and other common water heater issues.


Sediment buildup in the tank can reduce your water heater's energy efficiency and also clog your water lines.


Refer to your owner's manual for official maintenance instructions.


Tank Water Heaters


Most types of tank water heaters require flushing at least once per year. If you live in a hard water area, you may need to flush your water heater more often. That's because hard water contains a higher concentration of minerals, increasing the risk of sediment accumulation inside your water heater.


Tankless Water Heaters



Tankless water heaters don’t require flushing because they do not have a tank; however, many tankless water heaters require descaling.


How often you should flush or descale a water heater depends on its type and model. You should always defer to the instructions in your manufacturer's handbook to maintain your water heater correctly.



Explore our collection of A. O. Smith product literature to find the resources you need for your specific model.

How to Flush the Tank

Step 1: Turn Off the Heating Source


You should turn off your water heater's heat source before flushing it to reduce the risk of scalds. If you have a gas model, turn off the gas valve by moving the dial on your thermostat to the "OFF" position to extinguish the pilot light. Switch off an electric water heater by turning off the electricity supply at the breaker or disconnect.

Turn off power at breaker
Set the pilot light to OFF

Step 2 - Connect a Hose


Connect a garden hose to the tank's drain valve. Place the hose’s draining end in an area that can handle several gallons of hot water.

Attach a hose to the drain valve
Water hose to drain

Step 3: Open the Drain Valve


Open the drain valve manually or with a flathead screwdriver to release water from the tank. Sometimes, sediment buildup inside the tank can clog the drain valve and prevent you from removing the water. Call a plumber or service technician for assistance if you can't flush the tank.


Monitor the water coming from the drain valve and continue flushing the system with cold water until you no longer see sediment flowing from the tank.

Unscrewing the drain valve
Clear water draining

Step 4 - Close the Valve


Close the tank drain valve, disconnect the hose from the valve and close the pressure relief valve. Open all the hot-water spigots in the house to remove any air that may have been introduced into the system. Close the spigots once air stops coming from the faucet. and turn on the cold-water inlet to the tank.

Unscrewing the drain valve
Hot water from faucet

Step 5 - Turn the Unit Back On


Close each hot-water spigot as water begins to flow from it. After closing all the spigots, Turn on the electricity to the water heater, or turn the gas switch to run. Following the instructions on the water heater, the pilot light may need to be relit.

Unscrewing the drain valve
Hot water from faucet
Return to Task List

Adjusting the Temperature

Water that’s too hot or too cold is one of the most common issues with water heaters. Fortunately, this water heater maintenance issue is one of the easiest to service simply by adjusting the thermostat.

Step 1 - Turn Off the Unit

Turn off the electricity to the water heater. If this is a gas water heater, skip to step 3.


Step 2 - Open the Access Panel 

Use a screwdriver to remove the access panel that’s typically found on the front of your water heater. Remove the panel carefully, making sure to avoid wiring and components.

Unscrewing the drain valve
Opening electrical panel door

Step 3 - Adjust the Temperature 

Locate the thermostat temperature dial, control knob or LCD display. Once you determine the current setting, adjust the temperature to fit your household needs, which is typically no higher than 120 degrees Fahrenheit.


Remember to be careful when adjusting your unit’s thermostat. Setting the temperature too high will create dangerous, scalding hot water, and setting it too low can allow bacteria to grow.

Adjusting the temperature
Adjust the temperature to 120

Step 4 - Replace the Cover

Replace the cover, and turn on the power to the water heater. Monitor the new temperature and make adjustments as needed by following these steps again.

Closing electrical panel door
Unscrewing the drain valve
Return to Task List

Insulating the Pipes and Unit

Part of DIY preventative water heater maintenance is weather-proofing your unit to reduce freezing risks in colder climates. Proper insulation around the pipes and tank does this and more, preventing heat loss for improved energy efficiency.

Step 1 - Measure and Prep

Measure the pipes, and choose insulation materials like foam sleeves that precisely match the dimensions you need. Prepare the insulation material according to instructions.


Step 2 - Install Insulation and Tape Seams

Install the insulation materials, starting with the water heater tank and working your way out. Use foam tape to secure the insulation so that there are no gaps or overlapping areas.

Insulating the pipes
Return to Task List

Handling Leaks and Drips

Follow these instructions on how to handle leaks and drips.


When servicing your water heater, you may find that you’re getting leaks or drips. Most leaks are caused by faulty water supply connections, so use good materials, proper techniques and check your work carefully. Compression fittings are easier to install for DIYers than copper pipes, which need to be soldered.


Drips from the temperature and pressure (T&P) relief valve discharge pipe usually mean a thermal expansion tank is needed or your water pressure is too high.

Step 1 - Turn Off the Unit


Turn off the electricity to the water heater or turn off the gas to extinguish the pilot.

Turn off power at breaker
Turn off at breaker
Set the pilot light to OFF

Set pilot to "Off"

Step 2 - Pull the Trip Lever

Position a bucket to catch water from the pressure relief valve if it doesn’t have a discharge pipe, and then pull the trip lever on the valve to release the water. This will flush any material that could be stuck in the seal. Be careful, as the water can be very hot.


If you don't see any water coming out of the T&P valve, drain the tank and replace the valve. If the valve continues to drip and you have proper water pressure and a correctly charged expansion tank, Replace the T&P valve.

Position bucket to catch water
Release T&P valve

Step 3 - Replace the Valve

To replace the valve, remove the discharge pipe, and unscrew the valve from the water heater. Note the stem length and buy an exact replacement.


Screw the new valve into place, tightening with a wrench. Reattach the discharge pipe, turn on the water, and reconnect the electricity or restart the pilot light according to the manufacturer's instructions.

Removing the discharge pipe
Pressure relief valve
Return to Task List

Frequently Asked Hot Water Heater Maintenance Questions

How do you maintain a tankless water heater?

Caring for a tankless water heater ensures a long lifespan. Just like with a regular water heater, these appliances need to be descaled and inspections. You should also keep watch on the inlet filter regularly to keep it free of debris.



What’s a good annual water heater maintenance checklist?

Servicing your water heater each year helps prolong its life and increase energy efficiency. Care for your unit by checking these common issues annually:

  • Check for leaks.
  • Flush the tank.
  • Test the temperature and pressure relief valve.
  • Inspect the sacrificial anode.
  • Clean air intake vents.
  • Check the venting system.
  • Insulate the pipes and tank.
  • Check thermostat settings.
  • Inspect electrical connections and tighten if necessary.
customer using phone

Not sure which product is right for you?

Take our water heater selector quiz to find the correct water heater for your home.

Plumbing Professional

Find A Local Water Heater Pro

A. O. Smith water heaters are professionally installed by local independent contractors.

Why A. O. Smith?

 
market_leader
Market Leader

A. O. Smith is a leading manufacturer of both residential and commercial water heating technologies, including the #1 most specified commercial water heater.

creating_solutions
Commitment to Innovation

For more than 145 years, we’ve developed state-of-the art products that push new boundaries and improve the lives of our customers.

support
Best-In-Class Support

We combine cutting-edge technology with committed people who take pride in providing the very best support for our customers.

unmatched
Unmatched Quality

Our products are put through rigorous quality and endurance testing so now matter where hot water is needed, A. O. Smith can provide a solution you can count on.

Learn more about A. O. Smith