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Replacing a water heater is not cheap. What most homeowners don’t realize is that one small, inexpensive part—the anode rod—is what protects the tank itself from rusting out.
The simplest thing you can do to prolong the life of your water tank is monitor the condition of this metal rod. By nature, it'll slowly sacrifices itself so the tank doesn’t corrode, but you'll want to replace it before it deteriorates itself.
What Is an Anode Rod and What Does It Do?
“The anode rod is simply a long metal rod, usually made of magnesium, aluminum, or a zinc-aluminum blend," describes Tom McConahay, Senior Manager of National Plumber Support at Rheem Manufacturing. "It's suspended inside your water heater tank."
He continues, describing the intensity of the elemental reactions that take place in the tank. "The anode rod is often called the ‘sacrificial rod’ because it attracts the minerals that would otherwise corrode your tank. Over time, the rod itself deteriorates, and if it’s not replaced, the tank lining becomes vulnerable to rust and leaks."
In short, the anode rod takes the hit for your tank. It corrodes first, pulling minerals and corrosive elements toward itself instead of the tank’s steel walls. Once the rod is gone, your tank becomes the target—and that’s when leaks start.
"We recommend homeowners check the anode rod every 2–3 years or more frequently if you have very hard water," notes McConahay. "If it’s corroded down to about ½ inch thick or coated in calcium, it’s time for a replacement."
We have a tankless system. Do we have to worry about the anode rod?
No, tankless systems aren't affected by the effects of standing water because they don't hold water. If you have a tankless system, this is not a chore for you.
How to Check for Damage
You don’t need to be a plumber to check an anode rod.
The common signs of wear aren’t always visible from the outside, but a few clear indicators suggest that your water heating system is failing.
- The tap water from your faucets smells (or looks) off. "If the hot water has a rotten egg smell or looks rusty and discolored, it means the rod has stopped doing its job and the steel tank is starting to rust," warns McConahay.
- The hot water heater makes loud noises. "If your tank makes loud popping or rumbling noises while heating, it can suggest heavy mineral buildup that the rod is no longer preventing," shares McConahay.
- Do a visual inspection. "Homeowners can turn off the power and water, drain a few gallons, and pull the rod out from the top of the tank," notes McConahay. "If the rod is worn down to the thickness of a pencil (about 1/2 inch) or if the steel wire core is showing, it needs to be replaced right away."
Quick checklist:
- Hot water smells like sulfur or rotten eggs
- Rust-colored water or sediment buildup
- Loud popping or rumbling from the heater
- Anode rod less than ½ inch thick
- Exposed steel wire core on the rod
How to Replace or Order a New Rod
This is a quick 15-30 minute project, and yes, you can do it yourself.
It's as simple as reversing the steps that you took during a visual inspection.
Consider the following before you order a replacement anode rod:
- Solving odor problems: "If the hot water has that unpleasant rotten egg smell, which is caused by bacteria reacting with the metal, homeowners should really look at a zinc/aluminum alloy rod or upgrade to an electric (or powered) anode rod to actively combat the odor-causing issue," recommends McConahay.
- Opt for cost savings: A magnesium rod is usually the most economical option. Be aware: they may need to be replaced more often.
- A solution for tight spaces: “If there’s less than 44 inches of clearance, homeowners should purchase a flexible, segmented rod. These come in short pieces that snap together, making it much easier to install them into the tank in tight spaces.”
It's also smart to check the owner’s manual before ordering a new rod: “Regardless of the system, whether it’s a brand-new installation or an existing unit, consult the owner's manual for specific rod compatibility."
And, if this all feels like too much (or if the old rod is completely stuck), call a local plumber that can help you with the repair.
FAQ
How often should I replace the anode rod?
For most homes, every 3-5 years is typical. If you have hard water or notice odors in your hot water, check it more often. Waiting too long can lead to tank damage that no rod can fix.
Can I switch to a different type of anode rod than the one my tank came with?
Yes, many homeowners do. If your tank originally came with a magnesium rod but your water has a strong odor or high mineral content, switching to an aluminum-zinc alloy or powered anode rod can make sense.
Just make sure the new rod matches your tank’s size and threading.
And... always double-check your owner’s manual before ordering, or take the old rod to a hardware store for comparison.
What if my water heater is older... does it still make sense to replace the rod?
If your tank is less than 10 years old and still in good shape, replacing the rod can absolutely buy you more time. But if it’s already leaking or heavily rusted, a new anode rod won’t reverse the damage. At that point, it’s usually better to start planning for a full replacement rather than putting money into temporary fixes.
What happens if I skip replacing it?
Without the anode rod, the tank itself will rust. Once corrosion eats through the lining, leaks form. At that point, the only fix is a full water heater replacement. A $20 rod can save you from spending over $1,000 on a new water heater.
