Water Heater Anode Rods Explained: The Part That Saves Your Tank
The anode rod is a sacrificial metal bar that prevents your tank from rusting. Replacing it can double your water heater lifespan.
Safety Disclaimer
Water heater maintenance involves working with pressurized systems, scalding hot water, and potentially hazardous electrical or gas connections. Always shut off power (electric heaters) or gas supply (gas heaters) and allow water to cool to a safe temperature before beginning any maintenance. Wear appropriate safety equipment including gloves and eye protection. If you're uncomfortable with any step, contact a licensed plumber.
What Is an Anode Rod?
An anode rod is a metal rod (usually magnesium or aluminum) suspended inside your water heater tank from the top. It is designed to corrode instead of your tank. Through a process called galvanic corrosion, the anode rod attracts the corrosive minerals in your water, sacrificing itself to protect the steel tank walls.
Without an anode rod, your tank would rust through in 2-3 years. With one, tanks last 8-12 years.
Types of Anode Rods
For more on this topic, see our guide on Best Powered Anode Rods for Water Heaters (2025).
Magnesium Anode Rods (Most Common)
- Standard in most new water heaters
- Best for homes with soft water
- Corrodes faster in hard water or well water with high sulfate content
- Can produce hydrogen sulfide (rotten egg smell) in some water chemistries
For more on this topic, see our guide on When to Replace Your Water Heater Anode Rod.
Aluminum/Zinc Anode Rods
- Better for hard water and well water
- The zinc component helps reduce sulfur smell
- Corrodes more slowly than magnesium
- Some health concerns about aluminum leaching (minimal at water heater temperatures)
Powered (Impressed Current) Anode Rods
- Uses electrical current instead of sacrificial metal to prevent corrosion
- Never wears out (lasts the life of the heater)
- Eliminates rotten egg smell entirely
- Costs $100-$200 but pays for itself by eliminating rod replacements
When to Replace
Check your anode rod every 2-3 years. Replace it when:
- The rod is less than 1/2 inch in diameter (original diameter is typically 3/4 inch)
- The rod is coated in calcium deposits
- The steel wire core is visible through the corroded metal
- You notice rust-colored water or a rotten egg smell
How to Check and Replace (DIY)
- Turn off the water heater and cold water supply.
- Locate the hex head on top of the heater (the anode rod port).
- Use a 1-1/16 inch socket and breaker bar to loosen the rod. This may require significant force.
- Pull the rod straight up and out of the tank.
- Inspect the condition. If heavily corroded, install a new rod.
- Apply Teflon tape to the threads of the new rod and thread it into the port.
- Restore water and power.