Compare Aluminum vs. Magnesium Anode Rod: Pros and  Cons

Aluminum anode rodAnode rod

Is your water heater failing and producing a stinky rotten egg smell or leaks due to corrosion?

This article compares aluminum vs. magnesium anode rods so you can see the benefits and drawbacks of both when searching for one.

We will help you make an informed decision, so you can buy and install a high-quality anode that can successfully solve your hot water problems without affecting your comfort and wallet.

What is an anode rod, and how does it work? What are my options?

Anode rods are essential parts of all water heaters that use metal tanks. They protect metal components from corrosion while some also help reduce bacteria development as the main culprit of the stinky hot water.

Customers have a few options when shopping for an anode rod:

  • Aluminum anodes
  • Magnesium anodes
  • Zinc alloy anodes (often in combination with aluminum)
  • Powered anodes

The first three types are sacrificial as they "sacrifice" themselves to protect a water tank.

A powered anode is non-sacrificial and uses electricity to deal with the problems.

Things to consider

All anode rods provide corrosion protection and prolong the life of your tank-type water heater. So, the question is whether to buy a magnesium or aluminum anode.

Here are some important things to consider:

  • Cost. How much does it cost to buy an anode? The cheapest ones are around $15 while the most expensive are over $150.
  • Effectiveness. Does is it provide protection against corrosion, eliminate odor, and reduces sediment build-up.
  • How long does it last? A typical anode that is factory installed in the budget models can last 3-5 years, while the advanced heaters and high-quality anodes can last up to 20 years.
  • Does it need maintenance?
  • Tank size. Anode rods come in different lengths, so you should select the element carefully.
  • Water characteristics. Is water hard or soft? Not all anodes work the same.

Aluminum anode rods - Benefits and drawbacks

Aluminum anode rodAluminum anode rod

Aluminum anode rods are cheap, lightweight, and soft, making them easy to manufacture, bend, and install. The rod is installed inside the threaded port at the top of the unit. It looks like the head of a bolt.

Homeowners can also buy rods with a combination of aluminum and zinc for greater benefits in some cases.

It is recommended to replace anodes every 5 years, but it depends on the quality, water chemistry, and level of erosion. As per manufacturers, when the inner rod becomes quite exposed (consumed by more than 50%), it is time to replace it.

Be aware that water softeners and hard water can shorten the anode's life span.

Since aluminum anode rods are the most common type, their price is also lower - from $15 to $40.

Pros of aluminum anodes

  • The aluminum anode is better for hard water.
  • It lasts longer than the magnesium type.
  • Less maintenance involved
  • Cheap

Cons of aluminum anodes

  • Doesn't provide health benefits of the dissolved elements such as the magnesium type.
  • Higher aluminum levels in the water are a health concern, so drinking tap water should be avoided (or running cold water for a few seconds before cooking or drinking).
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Magnesium anode rods - Benefits and drawbacks

magnesium anode rodMagnesium anode rod

Magnesium anode rods are probably the most used ones for tank protection in residential water heaters. Due to their ability to release electrons easier, they would protect metal tanks better. That is why magnesium anodes will deteriorate faster in softer water and water with lower PH levels.

These anodes are very sensitive to corrosive elements, so they can work well in soft water, which contains many corrosive particles. On the other hand, they would last less if exposed to water with a lot of minerals (hard water).

As the aluminum type, magnesium anodes can also last 5 or more years, depending on several factors, as mentioned before.

It is recommended for homeowners to check the tank lining so as the anode rod for corrosion. Magnesium anodes and corroded tanks can trigger an electro-chemical reaction and cause hydrogen gas to react with sulfur and bacteria, causing an odor and water leaks.

According to some studies, magnesium anodes can also provide some health benefits to the users.

Magnesium rods cost more than aluminum types, and you can get one for $30-$40.

Pros

  • Magnesium anodes are better for soft water
  • Dissolved magnesium also brings health benefits to the consumers
  • Affordable

Cons

  • Short life expectancy
  • Requires frequent inspection and replacement
  • Do not function well in hard water

So, which on is better: aluminum or magnesium anode rod?

As we can see from comparing aluminum vs. magnesium anode rods, both types are affordable and available in any hardware store. The kind you want to install depends on the water quality in your area/home and whether you want to replace an anode often or rarely.


Aluminum anodes are better for hard water or water with a lot of dissolved minerals, while magnesium works best in softer water. And both are meant for corrosion protection.

But, if you have a problem with the rotten eggs smell (stinky hot water), get a non-sacrificial powered anode rod, or a cheaper zinc alloy rod (sacrificial).

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