What Is The Purpose Of The Anode Rod In A Water Heater?

Your beloved water heater, it provides you with a warm place to bathe your body after a sweaty day at work, it gives you warmth and comfort as you wash your hands (hopefully) after you use the sink and it is what is required by dish washers.

Inevitably though, like just about all mechanical things on Earth your water heater will need servicing.

One of the most commonly overlooked or unknown things about a water heater is also arguably it’s most important feature; the anode rod.

Not knowing about this fixture inside of a water heater has costed people hundreds, if not thousands of dollars in water heater replacement fees without them even knowing about it.

So, what is the purpose of the anode rod in a water heater? The anode rod is designed to act as a less noble material than the Steel tank of the water heater. This is so that water will disintegrate the anode rod long before it does the water heater, thus lengthening it’s lifespan.

Anode rods come in different sizes, materials and costs and, like an oil change on a car, can make a big difference on the lifespan of your water heater.

Continue reading to learn more about the anode rod and why it’s important!

What Is The Purpose Of The Anode Rod?

The anode rod is a vital part of any hot water tank and shouldn’t be overlooked. The anode is a fitting that comes with just about every water heater (except tankless kinds) and consists of one of the following materials:

  • Zinc
  • Magnesium
  • Aluminum

This anode rod will essentially act as a focal point inside the tank to allow water and oxygen to focus on it and eat away at it slowly over time.

This rod is also sometimes referred to as a “sacrificial rod” because of it’s nature.

This rod threads into your water heater from the top and averages about 44″ in length, but both smaller and longer sizes are available for different sized tanks.

The rod has threads on the end of it which utilize teflon tape to provide a water tight seal between threads and tank which is very important.

To find out more about teflon tape, I wrote another article that goes more in depth and can really be a beneficial read if you’re ever planning on replacing your anode rod.

Why Do I Need An Anode Rod?

As mentioned previously, the anode rod is of utmost importance inside of the water heater.

The rod protects the inside of the water heater from naturally occurring rust which will deteriorate into your water stream and begin to cause leaks from your tank.

The rod greatly extends the lifespan of your tank by being the sacrificial lamb. Because Zinc, Magnesium and Aluminum are less noble metals than Iron or Steel they tend to deteriorate quicker.

I am no scientist, so I can’t give you the most scientific explanation of it, but essentially the rod will give off it’s electrons to the oxygen and water causing it to corrode.

Steel and Iron does this as well, and tanks are usually made from either of these two materials with a thin layer of glass to help protect it.

The reason the anode is the thing that deteriorates first is simply because the less noble materials give off their electrons at a quicker rate.

With water heaters costing what they cost plus installation, it’s a no-brainer why this rod is utilized.

Costs Of Replacing Your Water Heater Vs. Replacing Your Anode Rod

Price Of The Rod

Depending on the size of the rod required and the material you decide to go with, the rods can be fairly inexpensive and they can range anywhere from the 15$ mark for small water tanks up to and above 45$ for standard sized heaters.

You generally won’t need a plumber to replace your rod as it requires one tool, the rod itself, some teflon tape and quite a bit of elbow grease.

The tool is a 1 1/16″ socket wrench and can cost you about 25$ for the wrench + socket.

Price Of Water Heaters

A water heater is a bigger investment to make and can run you upwards of 600$ and greater depending on your sizing requirements, brand and type of tank (electric, gas etc.).

Price Of A Plumber

You will require a plumber to install a water heater for you if yours breaks down and it won’t be cheap. Add on to the expense of a new unit, and you’re looking at around 60$150$ per hour.

The plumber will most likely be the one to grab the tank for you, but will likely mark up the cost of the tank on the bill to cover time, labor and fuel to retrieve the water heater.

With shutting off the supply of water to the old tank, draining it, disconnecting it from it’s power or fuel source and hauling it away plus hooking up the new one, attaching the power or fuel source, hooking up the water you could be looking at upwards of 3 hours for the job.

Tips to reducing the cost of the plumber:

  • Picking the new tank up yourself and hauling away the old tank is great way to save a few bucks as this will be tacked onto the end bill.
  • Shut the water off to your water heater and drain the tank yourself. This could save you a bunch of money as this can take a bit of time to accomplish. Some experience is definitely required for this job.

Note – If ever you’re unsure about how to do any of the plumbing projects on your own, it’s best to just leave it up to the pro’s. When dealing with plumbing, you’re dealing with potential for water damage, leaks etc. that could end up costing you.

How Long Can You Expect An Anode To Last?

Your anode rod should be checked once at least every 3 years. However, typically the rods will last a solid 4-5 years total before they need replacing.

The reason to check every 3 years is to ensure the rod is still good. Different houses experience different variables including the mineral count in water, the acidity of the water, and whether or not there is a water softener.

Checking the rod early is very beneficial to you as it will allow you to nip any potential impending doom in the bum.

Spending the 20 or so minutes to check, plus the roughly 45$ to replace (if needed) could save you some serious coin down the line.

What You Want To Look For

When you take the rod out of the tank, you are looking for the steel wire of the anode rod to be exposed.

The general rule of thumb is if you can measure 6 inches of visible steel wire, than your anode rod needs to be replaced.

The less ‘less’ noble metal available for deterioration, the more the corrosion of the tank itself will occur.

Ways To Check If The Anode Rod Is Bad

Besides manually shutting the water off to the water heater, unscrewing the anode rod from the tank and visually checking to see if the rod is bad, there are some ways you are able to tell if the rod has gone bad.

  • Rotten egg smell comes from hot water side – If you notice that there is a distinct rotten egg odor coming from when you turn the hot water on from your taps, this could be a sign that your anode is starting to fail.
    • The rotten egg odor comes from when the water/oxygen starts reacting with the lining of the tank and starts deteriorating it.
    • If you notice the smell when you turn on the cold water supply as wellThis odor may also be a result of issues with your water treatment, if you don’t have water treatment or in your supply lines somewhere. It’s best to call a licensed professional at this point to help you determine the cause.
  • If you have a water softener – Unfortunately, even though water softeners are supposed to help with the hard water in your home, they can also react to with the anode rod itself causing it to deteriorate quicker. If you recently had one installed you may want to check your rod every 6 months.
    • For softened water, consider getting a powered anode rod like this one off of Amazon. This rod does not deteriorate and can last well past 6 years.
  • Manually unscrewing the rod – Sometimes you are required to unscrew the rod, and besides the typical corrosion down to the steel wire, there may be a few other things to look for when taking it out.
    • Calcium build up – It is possible to have a high presence of calcium in your water that builds up on the anode rod itself, thus rendering the rod significantly less useful and will corrode your tank quicker.
    • No corrosion – It is also possible that you have installed a rod that just isn’t working. If after a month of being in service the rod looks like you just took it out of the box, then it isn’t doing it’s job and your tank is suffering because of it. Consider getting a powered anode rod if this is the case.






Tyler Takacs

My name is Tyler, I live in Ontario Canada and enjoy learning about common plumbing issues in the household. I have spent just over three years in the trades as a plumbers apprentice, but am now onto a less physical job. I still enjoy studying and learning about my own house's plumbing as well as finding ways to help others with their issues.

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