What is an Anode Rod in a Water Heater?

Last Updated On May 23, 2024

Updated on April 25, 2022



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What is an anode rod in a water heater

So, what exactly is an anode rod in a water heater? You may have heard about this very important sacrificial rod in the past, wondering what it does, or when it needs replacement. 

In this PlumbingNav review, you will learn: 

  • What is an anode rod?
  • How does the anode rod work?
  • What metals are anode rods made of?
  • How do you troubleshoot anode rods for replacement?

Read on to learn exactly what your hot water heater anode rod is, how it functions, its average lifespan, and how you can troubleshoot issues.

Let’s get started!

What's In This Guide?

      What is an anode rod in a water heater?

      The anode is a metal rod that serves an important function inside your water heater tank. It’s found in both gas and electric tank models. The anode rod can prolong the life of your water heater unit by subverting corrosive activity that is normal when water contacts metal.

      In other words, you want the anode rod to corrode because this diverts this activity away from your actual tank.

      It can and should be replaced at regular intervals based upon water quality, age of installation, and its condition. Although overlooked and out of sight, it’s an important component of the water heater that can save your equipment and also money over time.

      How does a water heater’s sacrificial anode rod work?

      The anode rod is also known as a sacrificial rod or a lure for all the ‘bad’ elements in your water heater. This sacrifice acts as a kind of bait for the corrosive elements, which are natural when steel comes in contact with water. These occur from oxygen, the acidity of the water, and of course heat.

      The ‘sacrifice’ comes in when you realize the rod takes on almost all the corrosion and will prevent your water heater tank itself from rusting, that’s when you’ll have bigger problems–replacement or critical repairs.

      How crucial is the purpose of the anode rod in a water heater?

      The water heater anode rod function often goes unnoticed, but it performs a crucial role in extending the life of your unit. The anode rod purpose can be viewed as similar to a lightning rod or grounding wire.

      It absorbs the expected, inevitable, yet unwanted activity that would otherwise cause your water heater tank to rust from the constant water-on-metal contact. It also releases electrons into the water heater tank. If you remove this important element, your water heater will indeed experience early corrosion and have a shorter life span.

      Water heater tanks are manufactured with a protective layer of material lining the inside of the tank. This can range from ceramic which is common in Rheem units, to an ultra-thin glass layer which was originally developed by A.O Smith.

      While these work extremely well, they are never 100% guaranteed to protect the life of your unit’s tank. Corrosion will still occur naturally over time.

      So, the crucial purpose of the sacrificial anode is to “absorb” or pick up the slack by attracting these unwanted elements from your water and keeping them off the metal tank’s surface as much as possible. This encourages a longer lifespan for your unit.

      did you know sacrificial anode rods and how they work

      What metal is a water heater anode rod made of?

      The anode rod can be made of aluminum, zinc, magnesium, or a combination of these. It’s the anode rod that is on the front-lines, fighting the corrosion from within the tank of your gas or electric water heater unit.

      The integrity of the rod will diminish over time, and this is by design. The acids in the water attack the steel of the sacrificial anode rod. It may take a few years, but it’s going to happen. This is expected, and one reason why you need to inspect it periodically.

      How do I know if my anode rod is bad or ready for replacement?

      Just like other plumbing items, you should inspect your water heater anode rod every three to five years to assess corrosion. Checking for tank corrosion should be part of your water heater maintenance. There are some things you can look for to identify anode rod corrosion.

      One sign to be aware of is if your water heater makes popping noises or other loud sounds while heating up. This can be an indication of corrosion in your tank lining. Note: If you hear whistling noises from your tank, this is a cause for safety concern.

      Another sign is smelly water which can be the result of the sediment buildup or sulfites previously mentioned. If this occurs intermittently, it’s not a problem. However, if this smell becomes regular and persistent it can point to a bad anode rod if sanitizing your tank with hydrogen peroxide didn’t clear up the odor.

      Of course, a magnesium rod is known for producing these smells as it breaks down, and while not an overt health concern, some say it is worth monitoring.

      See this related post for a detailed breakdown between aluminum vs. magnesium anode rods.

      Are there other things to look for to assess the lifespan of the anode rod?

      Your best gauge is in the quality of your water itself. You may observe silt, grainy components or even sand in your water. One area these may be visible are on your sink faucets. The screens or faucet aerator can accumulate a slimy layer, or possibly even small sediments, which indicate your anode rod might be on its last leg. If your hot water has become cloudy, this can be another marker that it’s time to replace it.

      How often should you replace the anode rod in a water heater?

      A typical water heater anode rod lifespan is 5 years. A gas water heater anode rod and electric are the same, in case you’re wondering. The minerals in your local water will affect the length of time yours will last.

      A good rule of thumb is to check your hot water heater anode rod around the 3-year mark. However, manufacturers will recommend that you perform an annual inspection on your anode rod. We think this is a bit overkill, but, if you’re an overachiever you can mark your calendar and inspect it every year.

      Does a water heater anode rod for well water last as long?

      Do you live on a property with a well? Well water sometimes contains more minerals than treated city water. This is often referred to as “hard water”, which can also affect the replacement life.

      Your water heater anode rod for well water should be checked every 3 years. If you recognize especially hard water, such as water stains on counters, sinks, and showers, this is a good indication that your anode might be working overtime.

      This will affect how often you need to change your anode rod in the water heater if you live on a well. Your replacement options can be determined based on budget, mineral composition, and the location of your water heater tank. These include zinc, magnesium, and aluminum anode rods. You can also look into a powered anode or flexible one, if your unit is located in a tight space.

      How often should you change the anode rod in a water heater with a water softener?

      Do you have a water softener? Many people who have hard water do. The salt minerals can accelerate the deterioration of your anode rod, so keep this in mind if present in your household.

      Of course, there are always exceptions. Some hot water heater anode rods can last for 10 years or more, although, this doesn’t always mean they are effectively doing their job.

      Final Thoughts on Anode Rods for Water Heaters

      Now you know what a water heater anode rod is, what it does, and how often you need to check and change it. It’s an important yet often overlooked element in every water heater tank that needs proper attention and eventual replacement to extend the lifespan of your unit.

      This, along with other plumbing tips and tank water heater maintenance items can save you money on energy costs.

      Need to learn how to replace yours? Check out this article for detailed steps on how to change the anode rod in your hot water heater.

      FAQ’s About Water Heater Anode Rods

      What is an anode rod in a water heater?

      The anode is a sacrificial rod in the water heater tank used to attract corrosive elements from your water away from the metal tank. Also made of metal such as aluminum, zinc, or magnesium, it protects the tank by “sacrificing” itself for the sake of corrosion.

      How do I know if my anode rod is bad?

      Anode rod corrosion will become evident upon visual inspection, but may also be recognized by these symptoms: smelly water or film on the faucet aerator.

      What happens if your anode rod goes bad?

      Your water heater will still function if your anode rod goes bad, but you may experience premature hot water tank corrosion as a result. It is advised to replace it to prolong the life (and warranty) of your unit.

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