anode rod removal impact wrench
Handy Tools

A Comprehensive Guide to Anode Rod Replacement: Removing and Replacing with the Power of an Impact Wrench

Fred Bahnson 

Is your water heater showing signs of corrosion? Don’t worry! By replacing the anode rod in your water heater before it fails, you can effectively slow down the corrosion process and significantly extend the lifespan of your unit. In fact, it’s possible to double the life of your water heater with this simple repair. This comprehensive guide will walk you through the process of anode rod replacement, ensuring your water heater remains in optimal condition for years to come.

Why Replace the Anode Rod?

Most water heater tanks are constructed of steel with a thin glass lining to protect the metal from corrosion. Over time, the glass lining may crack, leaving the steel vulnerable to rust. To combat this, water heaters are equipped with a long metal “anode rod” that attracts corrosive elements present in the water. However, when the anode rod becomes heavily corroded and can no longer perform its function, the tank will begin to rust, leak, and require replacement. By proactively replacing the anode rod approximately every five years, you can effectively double the lifespan of your water heater.

Understanding Anode Rods

Anode rods are typically made from magnesium, aluminum, or aluminum/zinc alloy. Aluminum replacement rods are readily available at home centers. In most cases, the hexagonal head of the rod is visible on the top of the water heater. However, if you can’t locate the hex head, consult your owner’s manual, as the rod may be positioned under the water heater’s sheet metal top or connected to the hot water outlet nipple. It’s important to note that a few newer plastic-lined tanks may not have anode rods that require replacement.

Preparations Before Replacement

Before you begin the anode rod replacement process, take the following precautions:

  1. Close the shutoff valve and turn on the hot water at a faucet to relieve pressure.
  2. Turn off the electricity or gas supply to the water heater.
  3. Open the drain valve near the bottom of the tank and drain several gallons of water. Caution: The water may be hot!
  4. Drain some water from the tank to inspect for rust. If you observe rusty flakes (not just orange water, which can be caused by corroded pipes or well water), it may be time to consider a new water heater. However, if the water appears clean, proceed to inspect the anode rod’s condition.

Removal of the Old Anode Rod

To remove the old anode rod, you’ll need the following tools:

  • Air compressor
  • 1/2-in. drive impact wrench
  • 1-1/16-in. socket

If you don’t have an impact wrench, consider purchasing an affordable one (approximately $30) for this project. Breaking free a corroded anode rod can be a challenging task, even with a breaker bar.

  1. Turn off the power or gas supply to the water heater.
  2. Close the cold-water valve at the top of the tank and drain off several gallons of water.
  3. Use the impact wrench to loosen the hex head of the anode rod. Once loose, unscrew it the rest of the way by hand.

Hint: The hex head may be concealed under a plastic cap. Uncover it and lift it to inspect its condition.

Installing a New Anode Rod

Now that the old anode rod has been removed, it’s time to install a new one:

  • Purchase a new anode rod from a home center or online retailer. Consider installing a flexible rod if you have limited clearance (less than 44 inches) above your water heater.

Turn on the water supply, power or gas, and burp the air from the system. 3. Regularly check the condition of your anode rod every three years to ensure optimal performance.

Dealing with a Stubborn Anode Rod

In some cases, the anode rod may be stubbornly stuck due to corrosion. Follow these steps to overcome the challenge:

  • Spray a lubricant, such as WD-40, on the hex head of the anode rod and allow it to penetrate for a few minutes.
  • Increase your torque by slipping a “cheater” pipe over the wrench handle.
  • If the weight of the water in the tank causes it to move, have a helper stabilize it to prevent any accidents.

When the threads break free, carefully inspect the area around the hex head for any signs of water leakage. If leakage is present, drain the tank further. If overhead clearance is limited and you’re unable to remove the rod in a straight line, gently bend it as you extract it. When purchasing a replacement rod, opt for a flexible and segmented version. Before turning on the water and restoring the power or gas supply, drain an additional gallon of water from the tank to flush out any remaining debris.

Tips for Choosing an Anode Rod

Consider the following tips when selecting an anode rod:

  • New vs. Used: Anode rods are designed to attract corrosive elements in the water, protecting the vulnerable steel liner from corrosion. While a magnesium anode rod offers better tank protection, it doesn’t last as long as an aluminum/zinc rod.
  • Smelly Water: If you have smelly water, aluminum/zinc rods are recommended and are usually more affordable. However, it’s advisable to consult a water treatment specialist before switching to an aluminum rod to ensure compatibility with your water supply.

Tools and Materials Required

To successfully replace the anode rod, gather the necessary tools and materials before starting the project:


  • Air compressor
  • Bucket
  • Impact wrench
  • Rags
  • Socket/ratchet set


  • Anode rod
  • Cheater pipe (steel pipe that fits over the socket wrench handle to increase torque)
  • Spray lubricant
  • Teflon pipe thread sealant

By following this comprehensive guide and taking proactive measures to replace your water heater’s anode rod, you can effectively prolong the lifespan of your unit and prevent premature rusting or leaks. Remember to prioritize safety by turning off the power or gas supply and taking necessary precautions throughout the process. Enjoy the benefits of a well-maintained water heater and the peace of mind it brings.