How to Replace an Anode Rod
Updated February 20, 2026
Swap the sacrificial anode rod in your water heater to prevent tank corrosion, eliminate rotten egg smell, and extend the unit's lifespan by years. $20-30 part.
Overview
The anode rod is a metal rod inside your water heater tank that corrodes on purpose so the tank does not. When it is used up, the tank starts rusting from the inside. That means rusty water, rotten egg smell (from magnesium rods reacting with bacteria), and eventually a leaking tank that needs full replacement. Checking and replacing the anode rod every 3-5 years is the single best thing you can do to extend a water heater's life. A $20-30 part can add 5+ years to a $1,000+ appliance.
What You'll Need
Safety First
- Turn off the heat source and let the water cool before working on the tank. Hot water under pressure can cause burns.
- The anode rod is under pressure. Open a hot water tap to relieve pressure before attempting to loosen the rod.
Step-by-Step Instructions
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Turn Off Heat and Water Supply
Gas heater: turn the gas valve to PILOT or OFF. Electric heater: turn off the breaker. Turn off the cold water supply valve above the heater. Open a hot water faucet nearby to relieve tank pressure and break the vacuum. Let the water cool for at least 2 hours if possible.
Tip: You do not need to drain the tank to replace the anode rod. Just relieve pressure. Some water will spill when you pull the rod -- have towels ready. -
Locate the Anode Rod
The anode rod threads into the top of the tank. It is either a separate hex-head fitting on top or integrated into the hot water outlet nipple. Most have a visible hex head (1-1/16 inch) on top of the heater. Some are hidden under a plastic cap. Check your water heater manual if you cannot find it.
Tip: If the heater is in a closet or tight space with low clearance above, you may not have room to pull a full-length rod straight up. Flexible or segmented anode rods ($25-40) are designed for exactly this situation. -
Break the Rod Loose
Use a 1-1/16 inch socket on a breaker bar (or a large adjustable wrench). This is the hardest part -- the rod is often corroded and seized. You need leverage. Brace the tank: have a helper hold it, or wedge it against the wall. Turn counterclockwise. If it will not budge, apply penetrating oil around the hex fitting, wait 15 minutes, and try again. A breaker bar with a cheater pipe gives the leverage you need.
Tip: An impact wrench (cordless or air) makes this dramatically easier. If you have one or can borrow one, use it. Breaking a seized anode rod by hand with a wrench is genuinely difficult. -
Remove and Inspect the Old Rod
Once loose, unscrew by hand and pull straight up. It will drip. The rod is 3-4 feet long -- make sure you have clearance. Inspect it: a healthy rod has most of its metal remaining. A depleted rod is thin, pitted, or reduced to the steel wire core. If most of the metal is gone, you waited too long -- but the tank may still be OK.
Tip: If the rod is mostly gone and your water has been rusty or smelly, the tank lining may already be compromised. Replacing the rod now will slow further damage but cannot reverse existing corrosion. -
Install the New Rod
Wrap the threads of the new rod with 4-5 wraps of Teflon tape. Insert the rod into the tank opening and thread by hand. Tighten with the socket or wrench -- snug plus a half turn. Do not overtighten. The fitting has a rubber washer that creates the seal.
Tip: Aluminum vs magnesium: magnesium rods protect better but can produce rotten egg smell in water with sulfur-reducing bacteria. If you have had smell issues, switch to aluminum or a powered (electronic) anode rod. -
Restore and Test
Turn the cold water supply back on. Let the tank fill (you will hear it). Once water flows steadily from the open hot water faucet (no air), close the faucet. Turn the heat source back on. Check the anode rod fitting for leaks -- a small drip usually means not enough Teflon tape. Tighten slightly or reapply tape.
Tip: Run hot water for a few minutes at multiple faucets to flush any debris dislodged during the rod swap. Check aerators for sediment particles.
Pro Tips
- Check the anode rod every 2 years after the 3-year mark. Pull it partially out and look. If more than 50% of the metal is gone, replace it.
- Powered anode rods ($50-100) use a small electrical current to protect the tank instead of sacrificing metal. They never deplete, eliminate rotten egg smell, and last the life of the heater. Worth the investment on newer tanks.
- If your water heater is over 10 years old and the anode rod is completely depleted, you are on borrowed time. Start budgeting for a replacement heater even if you install a new rod.
- Water softeners accelerate anode rod consumption. Softened water is more corrosive. Check the rod every 1-2 years in softened water homes.
- Write the installation date on the rod hex head with a paint marker. Easy reference for when to check next.
When to Call a Pro
Call a plumber if you cannot break the anode rod loose (a plumber has impact tools and experience), if the fitting is stripped or cross-threaded, if the tank is leaking from the bottom (the anode rod is too late -- the tank needs replacement), or if you have a heat pump or tankless water heater with a different anode configuration.