How to Inspect and Replace a Sacrificial Anode Rod (Every 3-5 Years)

When there’s no sacrificial metal left on the anode rod, your water heater tank can rust out, eventually causing it to burst.

Anode rods generally can last about three to five years, but it really depends mostly on the quality of your water and how much water travels through your water heater. By checking the condition of your anode rod every 3 years, you can reduce the chances of a leak, improve the quality of your water, reduce water heater wear, and tear, and save a lot of money.

How Do Sacrificial Anode Rods Work?

The most important part of a water heater is the sacrificial anode rod. It takes on all the damage, so your tank and pipes don’t have to. Additionally, a healthy anode rod reduces the amount of sediment at the bottom of your tank which can raise energy bills.

Sacrificial anode rods come in one of three materials:

  • Magnesium
  • Aluminum
  • Zinc

Since water wants to attack the steel-lined water tank and any metal pipes in your home, a more reactive (least noble) metal is chosen for the sacrificial rod.

The sacrificial anode rod will corrode away completely before the water begins to attack the steel water tank. As long as anode rods are regularly checked and replaced, your water heater tank will be protected from corrosion.

Top 10 reasons to replace your anode rod

  1. You want to extend the lifespan of your water heater. It will cost you much less to replace the anode rod than your water heater.
  2. Water heater pan has started to accumulate water.
  3. Water softeners can accelerate anode rod corrosion.
  4. Acidic water can accelerate anode rod corrosion.
  5. The water heater makes loud or multiple popping noises when heating up, signaling potential corrosion in your tank lining.
  6. It’s been 3 years since the last time you checked/replaced the anode rod.
  7. Faucet aerators appear to clog more frequently.
  8. You notice a slimy gel substance when cleaning the faucet aerator.
  9. Gritty, sandy, or bad-smelling water.
  10. High water heater bills. Old anode rods increase the sediment at the bottom of the tank which inhibits heat transfer.

How to Replace a Sacrificial Anode Rod

Protect your water heater from corrosion by learning how to replace the anode rod.


  • Bucket or hose to remove a couple gallons of water
  • A high-quality 6-point 1-1/16” impact socket
  • Possibly a helper (or two)
  • Replacement sacrificial anode rod


  1. Turn Off Water and Fuel Supply (Gas or Electric)
    Locate the gas line near the bottom of your water heater. Turn off the gas by rotating the valve clockwise—it should be perpendicular to the pipe. If you have an electric water heater, locate it’s corresponding breaker in the main service panel and flip it off.
    After shutting off the gas or electric, turn the cold water supply off—it’s normally on the right side of the unit up at the top. The cold water line can have either a ball valve (handle that goes parallel or perpendicular to the pipe) or gate valve (handle that you have to spin). Either way, turn the valve clockwise until it comes to a stop.
  2. Drain Some Water
    Drain a couple gallons of water—about 10% of the tank’s volume. You can use a large bucket or divert the water outside using a garden hose. Attach the garden hose to the “boiler drain” located on the bottom half of the tank.
    Some boiler drains have a handle; others, you will need to turn with a flathead screwdriver. Don’t want to drain too much water since the weight of a nearly full tank will help you when removing the anode rod.
  3. Locate Anode Rod
    Now, try to find the anode rod. Sometimes, you will need to remove the entire top lid to find it. More commonly, the anode rod can be removed without unscrewing the top cover. Look for the hex head on top of the unit.
    If there is a hex plug head on top, it will always be 1-1/16” (27mm). This is a rather large socket size. If you don’t have the right tool, investing in one is highly recommended as you will need it to regularly check the status of your anode rod. Get the heavy duty one!
  4. Loosen the Hex Head and Remove the Anode Rod
    The hardest part will be the loosening of the hex head. Pulling an anode rod out is not easy! It’s going to take a lot of muscle. While the weight of the water in the tank should help, you may need an additional person to help you hold the water heater while you loosen the hex head. Sometimes, two or three people are needed to hold the water heater in place. Do NOT twist the water heater—you could damage things like pipes and fittings.
    One trick for loosening the bolt is by using leverage. You can use a small metal pipe section to fit over the impact socket to extend the length and gain more leverage.
    Sometimes, the anode rod is just too hard to remove. In this case, contact a professional.
    Once the hex head is loosened, you can pull out the anode rod. If your ceiling is low or you have limited room, you may have to bend the anode rod to remove it. If this is the case, make sure you have a flexible/collapsible anode rod to replace it with.
  5. Install New Sacrificial Anode Rod
    Use Teflon® tape (plumber’s tape) to wrap around the joint threads of the new anode rod. Most people don’t have enough clearance for a regular anode rod, so get a collapsible anode rod instead.
    Once you get the anode rod inside, tighten it by hand until you cannot anymore. Then, use the socket wrench to tighten it a bit more, about 1/2 turn, 180 degrees. Do not tighten so hard that the water heater begins to move or twist.

Watch this video from This Old House for more information:

If you have any questions or need help with your water heater, don’t hesitate to contact Service Champions.

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