Water Heater Anode Rods: What Is It & The Best Way to Replace It

Ryan Womeldorf
by Ryan Womeldorf

Your water heater is a crucial appliance in your home. Without it, there would not be hot water available unless you got out a pot, put it on the stove, and boiled it up yourself. It is a convenience that many of us take for granted but sorely miss when it is not available.

One component of the water heater is the anode rod. What is it and what does it do? The anode rod is a sacrificial component. This steel core is wrapped in either magnesium, zinc, or aluminum and works to attract all the corrosive particles that collect in a water heater tank. The goal is to protect the liner, reduce the potential for an explosion, and to extend the life of the water heater. A quality anode rod can last 3 to 5 years.

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A Quick Note About Water Hardness and Sediment

For your water heater, perhaps its biggest enemy is sediment buildup. Sediment is a collection of the minerals that are found in the water in your area. This is known as the hardness of the water. Depending on where you live, that water can be quite soft with minimal minerals or hard enough that it requires intervention.

In either case, the water heater is susceptible to the sediment created by those minerals. If left unchecked, sediment can and will build up on the inside of the tank. It can wear down and corrode the liner of the tank over time. If left unchecked for long enough, it can make the tank much more susceptible to explosion as well.

In order to keep your water heater functioning properly and for a long time to come, there is a component meant to help protect it. That component is – you guessed it – the anode rod.

What is the Water Heater Anode Rod and What Does it Do?

To combat that sediment, water heaters have what is known as an anode rod. The anode rod is a sacrificial component. Wrapped in one of three different metals, it actively draws any corrosive particles away from the tank and to itself.

By attracting those corrosive particles, it not only extends the life span of the water heater, but keeps it protected as well. Those corrosive materials will not wear down the wall of the tank, either. If corrosion is allowed to build up, it can impact the tank in more ways than one.

For starters, corrosion can eat the liner and walls of the tank. When the tank becomes damaged enough, it will need replacing. Not only that, but the corrosion of the tank can lead to a potential explosion even under lower water pressure. The anode is there to literally take the abuse that the tank would otherwise be forced to endure.

The Different Types of Water Heater Anode Rod

When it comes to anode rods, there are more than a few to choose from. Each has its own distinct properties, lending advantages and disadvantages to its use. The three primary types are aluminum, magnesium, and zinc, though there are a few less commonly used types.

Let’s put a focus on the big three for now as they are the most commonly available. There is a good chance that if you have purchased a home, your water heater has a magnesium anode rod installed within.

Magnesium Anode Rod

As mentioned in the previous paragraph, magnesium is the most common type of anode rod there is. They are pretty cost-effective but that is not why they are used. Believe it or not, dissolve magnesium actually has health benefits when it gets into the water supply.

The main problem with a magnesium anode rod is that it can dissolve rather quickly. On top of that, it is not meant for homes that have particularly hard water. Corrosion from hard water can accelerate to the point that the rod won’t be able to provide long-term protection.

Aluminum Anode Rod

Aluminum anode rods are the cheapest that you will find out there. On top of that, it also happens to last the longest. Because of its durability and cost-effectiveness, it is perfect for homes that have substantial hard water.

The biggest issue with aluminum anode rods is that they should not be used for drinking water. You will have to have some sort of filtration system to drink water that has come from an aluminum anode rod water heater.

On the plus side, aluminum is ideal for tighter spaces. Its flexibility makes for an easier installation in those spaces, whereas a traditionally straight rod may not fit. Despite the issues with drinking water, aluminum rods are recommended if you live in an area that has hard water.

Zinc Anode Rod

This isn’t a pure zinc anode rod, to be clear. Zinc anode rods are actually aluminum but they have a tenth of zinc added in. You also will not find zinc anode rods installed on any water heaters straight from the factor.

If you deal with that rotten egg smell quite a bit (that is sulfur you are smelling, then zinc anode rods make for an excellent upgrade. The zinc helps to control bacteria growth within the water. It is the bacteria that causes the water to have that foul smell.

Because it is largely constructed of aluminum, it also has great durability, especially against hard water. Think of it as “aluminum plus” for anode rods or a water freshener to make it even more simple

Combination Anode Rods

There is one other type of anode rod and it is anything but common. A combination anode rod is just like your typical anode rod, the main difference being that it is attached to your hot water outlet. You won’t find this kind of setup on most water heaters and for good reason.

The main reason that you don’t see combination anode rods is that it is not only difficult to access, but difficult to service as well. This anode type gets installed on the interior of the pipe, making it far more difficult to reach. More often than not, replacing it means breaking the pipe to gain access and then having to replace the entire thing.

What is a Powered Anode Rod?

Unlike regular anode rods, which are sacrificial, a powered rod does not degrade. Instead, it uses electrical pulses to handle the corrosive elements that the traditional anode rod would typically attract to itself.

The pulse of a powered anode rod will scatter all of the harmful electrons, which keeps them from building up in the lining of the water heater tank. Whereas traditional anodes simply take the brunt of those corrosive materials, the anode rode disperses them.

There are more than a few advantages to having a powered anode rod. For one, they do not degrade. That means getting far greater life out of them and not having to replace them anywhere near as much. Also, like zinc anode rods, they prevent smelly water by killing all the bacteria that leads to that stinky, rotten egg smell.

They are much more expensive than traditional anode rods but for really good reason. If you want to safely and effectively protect your water heater tank without having to replace your anode rod, a powered anode rod is the way to go.

What is the Life Span of an Anode Rod?

There can be some variance to the life span of an anode rod depending on its type and application. Generally speaking, an anode rod will last somewhere in the three to five year range. That is provided that both it and the water heater are functioning properly.

If you live in an area that is higher in magnesium and calcium minerals and don’t have the anode to hold up to it, then it will likely be less than three years. It really all depends on the quality of the water in the area.

For those that live in an area with particularly hard water, a water softener can be a worthwhile investment. These softeners reduce limescale and calcium buildup exponentially over time. That can not only have a huge impact for the better on your water heater, but on things like pipes, taps, and other water fixtures as well.

How Often Should You Check Your Anode Rod?

Now that we know that the life span of an anode rod is in that three to five year range, you may be simply assuming to check on it during that time span. While you could do that, checking the anode rod should be part of the preventative maintenance checklist for your water heater.

It is a good idea to have your anode rod checked every two years. While the life span is a bit longer than that, having it checked every other year means knowing the condition and knowing if it is going to need replacing soon.

Remember that anode rods, particularly magnesium anode rods, can dissolve far more quickly in areas with hard water. Constant exposure to hard water can bring the life span of your anode rod down substantially.

Maintenance is Crucial for Your Anode Rod and Water Heater

One of the best ways to stay up with the condition of not only the anode rod but the water heater is to have regular maintenance performed. It is recommended that you have your water heater serviced twice each year.

Failing to have your water heater serviced can have serious repercussions. Not only can your anode rod become worn and ineffective, but rust and corrosion can build up in the tank. That’s not even mentioning potential issues with some of the crucial safety components in the water heater.

Do yourself the favor and have your water heater serviced twice per year. It is a quick, cost-effective way to prevent issues from popping up. Not only that, but it can help you get the longest possible life out of your water heater.

How to Tell if Your Water Heater Anode is Bad

Like any other component of your water heater, there are signs that the anode rod has gone bad. For starters, hot water will begin coming out with a funky smell or some discoloration. While that can be a sign that there are other issues at play, it is often times the anode rod that is bad.

Other than that, your anode rod will require checking to see what condition it is in. when it wears down to the point that there is no longer metal, it does nothing to protect the liner of your water heater. If you think that the anode rod has gone bad, here is how you do it.

Step 1: Shut Off the Water, Power, and Relieve the Pressure

Before you can do anything, there are three things that you need to first do. First and foremost, shut off the water. It kind of goes without saying but you should never perform work on your water heater with the water on. That can get messy.

The second thing to do is shut the power (or gas) supply off. With electricity or gas at play, things can turn dangerous in a heartbeat. Turn off the fuel supply to ensure that you are safe while performing the check.

Finally, turn on the hot water in a tub or sink somewhere for about a minute. By turning on the faucet after the water has been turned off, you relieve the pressure that is already built up inside of the water tank.

Step 2: Drain the Tank

With the pressure properly relieved, it is time to remove the water from the water tank. You should be draining the tank and flushing it at least once per year. If you haven’t done it before, this can be good practice.

Attach a hose to the water heater’s drain valve, which should be at the bottom of the tank. Put the end of the hose in a bucket, tub, or sink. Then drain out the several gallons that remain of hot water in the tank.

Step 3: Check for Sediment or Rust

Remember how we talked about draining and flushing the tank from time to time? Even if you have never done it, this is as good a time as any to check for sediment or rust in your drained water. Should the water be gritty, smell funky, or have a darker hue to it, then you should drain the tank in full and have it flushed.

If anything, you could be dodging a bullet and it will make sense if you get to the anode rod and it is totally dissolved.

Step 4: Hex Head Screws and Checking the Condition of the Anode Rod

Should the water look okay, find the six-sided screw head that is at the top of the tank. This is your hex head and it should be unscrewed most of the way using an impact wrench. You will want to unscrew it the rest of the way with your hand. Should the hex head be set below the top of the water heater, you will need a socket to reach it.

When the hex head has been removed, you should have access to the anode rod. If it is stuck because of corrosion, use a lubricant to loosen it before fully detaching it. With the anode rod totally removed, you can now freely check the condition.

Corroded anode rods will have pitting in most cases. But in extreme cases, there may be entire sections of the rod that are missing. For corroded rods, replacement is the solution.

Replacing Anode Rods

Knowing the life span of an anode rod is a good place to start. But what happens if you are checking on the condition yourself and discover it worn past use? When an anode rod is depleted, the metal will be gone and it will stop attracting those corrosive materials to it. When that happens, those corrosive materials can build up in your water heater tank.

It is always easier to bring in a professional to replace this component. They not only have done this before, but typically can troubleshoot the problem and deliver a replacement in a much shorter time than the average DIYer.

But if you plan on doing the job yourself, follow these steps.

Steps to Replace an Anode Rod

If you are wanting to save a few bucks on bringing out a professional plumber, changing out your anode rod is always a possibility. It helps if you have prior plumbing knowledge but it is not necessarily a must.

Keep in mind that the following directions should work on most modern water heaters. If it doesn’t, then replacing the anode rod can be far trickier. If you are ever unsure about what to do when replacing the anode rod, call in a professional instead.

Step 1: Finding the Anode Rod

Since we covered finding the anode rod in the section about checking its condition, you can just skip forward to accessing the anode rod. After the hex head top bolt has been removed, you may need a 1-1/16th inch socket in order to take the anode rod completely out.

If the rod is connected right into the hot water outlet, you will have to completely disconnect the hot water supply in order to properly access the anode rod. The good news is that those combination anode rods are not terribly common.

Step 2: Removing the Rod

This sounds easy but there is quite a bit that goes into the removal. For one, it is a good idea to have a second person there for the removal. Someone to hold the water heater will keep it from shifting and the supply pipes from potentially breaking.

Having proper clearance is ideal but not necessarily a reality. For height clearance issues, there is a chance that you might have to bend the anode rod to get it out. Never, ever hit it or use a hammer on the tank to remove the rod. Doing so could damage the inner lining of the tank, leading to a potential leak.

Step 3: Tough to Remove Anode Rods

Difficult to remove anode rods can be removed a couple of ways. The most commonly recommended method is with a lubricant like WD40 or Liquid Wrench. The downside is that they could leak down into the water heater and potentially contaminate the water.

You may also be able to use a breaker bar if the anode seal is rusted over. Good, firm pressure and a slow twisting motion should be enough to get even the most rusted of anode rods out of their positioning.

Step 4: Replace

With the anode rod now loosened, you should be able to remove it entirely. There’s a good chance that, if you are here, the anode rod is damaged or worn. Take a good look and verify that replacement is required.

If the anode rod slows only slight corrosion and still has its full length, then there is no need to dispose of it. Just make sure that you put new Teflon tape as well as pipe dope onto the threaded end of your anode rode in order to create a seal that is watertight.

Installing a flexible anode rod may be necessary if the water heater is in a space with limited height clearance. Just make sure that everything goes into place securely to prevent against potential leaking.

Step 5: Test it All Out

When you are confident that the new anode rod is in place, close everything up and turn on both the fuel/power and the water supply. The key here is that you will need to give the water heater about an hour to fully recover.

Make sure that you check the anode rod physically to ensure that there is no leaking. A leak is not cause for alarm it typically just means that you need to tighten the connection a little more using your socket piece.

Are All Anode Rods the Same Size?

Contrary to popular belief, anode rods are not the same size universally. Each of these rods not only differs in material, but in length as well. Also, depending on your water heater type, the rods will either be installed at the top or directly into the hot water outlet.

That said, the diameter is universal. At ¾” thickness, each anode rod is the same in that regard no matter the material or length. For the latter, anode rods come in lengths that range from 33 to 44 inches.

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The Final Word

There may not be a more important component to your water heater than the anode rod. Its sole purpose in life is to take the beating that was otherwise meant for the tank liner. By taking that beating, it saves the liner, saves the tank, and prevents major issues like explosion from taking place.

While there is not a ton of maintenance to be done on an anode right, frequent maintenance checks can give you an idea of its condition and whether or not it requires replacing. Ignore maintenance or other obvious signs that there is an issue and you run the risk of having a completely deteriorated anode rod that isn’t doing much to help your tank.

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Ryan Womeldorf
Ryan Womeldorf

Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.

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