How do I drain a water heater and replace the anode rod?

Cool the tank first, then cut the heat. A. O. Smith says to turn the heater off a few hours ahead so the water cools, and to wear thick gloves and safety goggles. For an electric unit, flip the breaker. For a gas unit, turn the gas control to OFF. Then close the cold water supply valve on the pipe feeding the tank.

Have a plan for the water. Use a hose rated for the discharge temperature and an approved location that can safely receive the water. A bucket fills fast, so keep towels close.

If you smell gas at any point, do not light anything or touch a switch. Bradford White's manual says to call your gas supplier from a neighbor's phone, and to call the fire department if you cannot reach them. More on this at pilot light out and a gas smell.

1. 1Power or gas off. Breaker off, or gas control to OFF.
2. 2Cold supply off. Close the valve on the cold line above the heater.
3. 3Hose on. Thread a garden hose onto the drain valve at the bottom of the tank and run it downhill to a drain.
4. 4Open a hot tap. Any hot faucet in the house. This lets air into the plumbing so the tank drains instead of gulping.
5. 5Open the drain valve. Some open by hand, some take a flathead screwdriver.
6. 6Flush if you want to. For a sediment flush, drain until the water runs clear. A. O. Smith's maintenance guide says to drain 2 to 3 gallons and, if the water is milky, drain the entire tank.

Drain water can be scalding. A. O. Smith also notes that sediment can clog the drain valve itself, and says to call a plumber if you cannot flush the tank. A drain valve that will not flow, or one that will not close afterward, is the first spot where DIY can stop being a good idea. Our full flush guide for Phoenix homes has the interval and the hard-water reasoning, so this page sticks to the job itself.

First identify the anode arrangement. Some heaters use a separate hex-head rod, others a combined hot-outlet anode or a powered system. Follow that model's procedure.

1. 1Find the rod. A separate rod may have a hex head under a cap; a combined outlet anode requires a different access procedure.
2. 2Get the water level below the opening. Drain a few gallons. If water comes out when you loosen the rod, stop and drain more.
3. 3Break it loose. A. O. Smith's maintenance guide calls for a 1-1/16 inch socket and an impact wrench. That tool specification is not universal. Use your manual's tool and access requirements; do not apply force that twists the tank or attached piping.
4. 4Lift it out. If the ceiling is low, A. O. Smith says flexible replacement rods are available where overhead clearance is tight.
5. 5Judge the old rod. A. O. Smith says that once the rod is mostly gone or 6 inches of core wire is exposed, the tank starts rusting from the inside out. The PNNL report adds two more replacement signs: a rod corroded to less than half its original diameter, or heavy pitting or splitting.
6. 6Seal the new rod's threads. Wrap them with Teflon tape or use pipe thread sealant, as the rod's instructions direct.
7. 7Thread it in and snug it. Use the manufacturer's specified tightening method and torque where provided. Hand-tight or "snug" is not a universal specification.

Do not leave the rod out. Rheem's manual says operation with the anode rod removed greatly shortens the life of the glass-lined tank and excludes warranty coverage.

Use a replacement approved for your heater, its fitting and your water treatment. A report from Pacific Northwest National Laboratory, prepared for the U.S. Department of Energy, lists the common options.

The report discusses how softening can accelerate anode consumption, and Bradford White's manual calls for more frequent inspection with softened water. On a softener, check the rod more often. See salt-based softeners and water heaters and whether hard water will ruin a water heater for more.

Some Bradford White models use a combination anode and hot water outlet nipple, per the manual. Replacing that one means disconnecting the hot water line, a bigger job.

Fill first, purge air, and only then bring the heat back.

1. 1Close the drain valve and remove the hose.
2. 2Open the cold supply valve.
3. 3Leave a hot tap open. A. O. Smith's drain guide says: "Continue running the hot faucet for at least 3 minutes to remove any trapped air from the system."
4. 4Check the rod fitting, the drain valve, and the connections for drips.
5. 5Then restore power or open the gas and relight the pilot per the manufacturer's instructions.

A. O. Smith's guide says to make sure the tank is completely full before returning to service, and that purging air is very important for electric units. Bradford White's manual says never to operate the heater without being certain it is filled with water. That's the step people skip.

Gas units: follow the lighting instructions printed on your heater. If the pilot will not stay lit, stop and see why a water heater pilot light won't stay lit.

Sediment leaves clues. A. O. Smith says popping, rumbling, or crackling during heating can point to sediment on the tank bottom, and that rust-colored hot water can mean the anode is used up. It also warns those symptoms can have several causes. Our page on popping and rumbling noises walks through them.

Manufacturers differ, so follow your own manual. A. O. Smith's maintenance guide says to check the rod at least every three years depending on water conditions, and every year with a softener. Bradford White's manual says every 2 years. PNNL reviews anode maintenance literature; use the actual model's interval and replacement criteria rather than treating that review as a new universal service schedule.

DIY is realistic if the drain valve works, the rod head is reachable, and you can spare a couple of hours. It gets harder fast in three cases:

• A seized rod. Corrosion can lock the head. An impact wrench helps, but a rod that will not budge, or a hex head that rounds off, needs a pro.
• A drain valve that clogs or leaks. A. O. Smith says to call a plumber if sediment blocks it.
• Tight overhead space or a gas unit you don't want to relight. Bradford White's manual recommends that the heater be installed and serviced by a plumbing professional, and says installation and service on gas models must be done by a qualified installer, service agency, or the gas supplier.

If the tank is old and leaking at the base, a new rod won't save it. See whether to repair or replace a water heater. HQ is licensed and insured, and gives free estimates and upfront pricing before work starts.