What Is a Water Heater Anode Rod (why you NEED to know)

Today, we’re focusing on one of the water heater’s less talked about parts: the anode rod. What is a water heater anode rod, exactly?

It’s basically a metal stick that hangs inside your heater. It works to preserve the heater’s tank from corrosion, thus helping to keep everything running smoothly.

Water heater anode rods are available in different types. Each type has its own lifespan, after which a replacement is mandatory. Continue reading to learn all about anode rods.

What Is a Water Heater Anode Rod

Can you imagine modern life without a water heater? It’d be very hard to bear without the hot showers and baths we enjoy. Not to mention all the appliances that rely on hot water, like the dishwasher and washing machine.

The water heater is possibly one of the hardest working appliances in your home. It provides everyone in your home with hot water at any given time of the day, year-round.

This is why anode rods are SO important!

Water heater anode rods are steel core wire surrounded by one of three types of metal. It’s attached to the top of the heater and hangs in the water.

In most water heaters, the anode rod has a hexagonal head, which is visible from the top of the unit. If you don’t see it on your heater, look for it near the hot water outlet inside the tank.

Still can’t locate it? Refer back to the manufacturer’s website or owner manual.

How Does an Anode Rod Work

Plumbing involves both water and metals, both of which aren’t quite fond of each other. When water and metals mix, they result in an electrochemical process known as galvanic corrosion. This is when two types of metal are immersed in an electrolyte like the water inside the tank.

So, the pipes are one type of metal and the steel lining of the tank is another. Add water to the mix, and you have the perfect recipe for galvanic corrosion.

To prevent this electrochemical process from wreaking havoc on the tank, we add a sacrificial anode rod. Its main purpose is to attract the corrosive elements in the water and keep them away from the steel lining.

As long as the rod is degrading inside the tank, the steel lining will remain rust-free. If the rod reaches a state where it’s thoroughly corroded and can no longer do its job, the tank will start to rust. When this happens, you’ll be forced to replace not only the anode rod but the entire water heater as well.

What Are the Different Types of Anode Rods

Anode rods are made from aluminum, magnesium, or aluminum/zinc alloy. They’re all metals that are more responsive to rust than the steel lining of the heater tank.


Almost all water heaters come with an aluminum anode rod as part of their standard equipment. This rod type is ideal for places with hard water and elevated pH levels. They’re cheap and will last longer than other types of anode rods.

Their one downside is that they pose a health risk. To prevent any health problems, don’t drink hot water. Additionally, run the cold water for a few seconds before drinking to wash away any aluminum residue.

Quick Products QP-AAR44 Aluminum Residential Anode Rod - 44" Length, 3/4" NPT


Magnesium anode rods do a better job of protecting the tank lining, especially if you live in an area with soft water. If you have hard water, though, magnesium rods won’t last as long as rods made of aluminum/zinc alloy. Yet, studies show there are health benefits to drinking water with traces of dissolved magnesium.

Magnesium Water Heater Anode Rod (44-inch Flexible) by Kelaro


Aluminum/zinc anode rods have a zinc-to-aluminum ratio of 1:10. The zinc helps eliminate sulfur smells coming from the water caused by the growth of iron bacteria. Such anode rods are pretty affordable and long-lasting.

About Fluid Aluminum Zinc Replacement Anode Rods for Water Heaters (Aluminum ZINC Complete KIT)

How Long Do Anode Rods Last

In general, water heater anode rods should last from three to five years. Since the rod is designed to attract corrosive elements in the water, it rusts fairly quickly.

The rod will continue to dissolve until it’s time to get a replacement. When it becomes so worn down that it can’t do its job any longer, the tank itself will start to corrode.

Waiting a long time before installing a new anode rod will shorten the lifespan of the heater. It can cause the water heater to malfunction and even start to leak.

To help preserve the water heater tank’s condition, it’s important to keep regular tabs on the rod. Then, as soon as you notice a chunk of the rod’s inner cable, it’s time to remove the old, corroded rod and replace it with a brand-new shiny one.

When Should I Replace the Water Heater Anode Rod

The best time to get the anode rod replaced depends on several factors. You have to take into account the quality of the water, how far it travels through the pipes, and whether it’s hard water or soft.

Making sure that the anode rod is always in good shape can help boost the life expectancy of the water heater. The good news is that anode rods are cheap and easy to install.

If you’re uncertain about the state of the rod in your heater tank, take a look at these situations. Do any of them apply to you? Then, it’s time to get a new anode rod.

  • You’ve had the water heater for over five years and haven’t changed the anode rod.
  • The water heater makes a popping noise when it’s heating up.
  • You notice a slimy substance when you’re cleaning out the faucet aerators.
  • The hot water starts smelling like rotten eggs.


Most people don’t give their water heaters a second thought as they go about their day. They also take the anode rod for granted, even though it’s part of one of the most essential appliances in your home.

So, what’s a water heater anode rod? It’s a metal rod that protects the metal lining of the water heater tank from rust and corrosion. This simple rod plays a crucial role in maintaining a rust-free water heater for many years to come.

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