Aluminum vs Magnesium Water Heaters? Which one is Best?

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Water heaters that are based on water tank systems use two types of anodes including aluminum and magnesium. To understand the importance of anode rods you must know the working of the water heater.

When the pressure builds up in the water tank it affects the steel rod. A combination of heat pressure and the acidic nature of water requires a balancing rod. This balancing rod is mostly made of magnesium or aluminum. These rods are placed in the water heater to absorb the damage caused by corrosion and must be replaced after three to five years. There are some pros and cons of using both types of anodes in a water heater. When comparing the two types of anodes, the following consideration must be kept in mind:

1. Durability

The rods placed in water heaters are mostly embedded to save the steel rod. The durability of an anode depends on how long it will last. Magnesium rods tend to corrode much faster than aluminum rods. The upper layer of the anode is chafed off due to electrolysis and must be changed after 3 to 5 years depending upon the use and type of water in the area.

Aluminum vs Magnesium Water Heaters? Which one is Best?

2. Blocked Water Lines

Aluminum rods are less advantageous as small pieces of the anode slowly fall off. As the anode rod continues to corrode the pieces of anode travel down the waterline. After some time, these pieces cause blockage in the water lines leading to a poor water supply. Magnesium rods are better as their pieces do not fall off into the water line and last longer.

3. Pricey Exchange

When making a decision based on the price of aluminum and magnesium rods, the best choice is an aluminum rod. They are cheaper than magnesium rods and are readily available. So if you are deciding whether the aluminum rod is better in terms of finances then it is the most reliable choice. 

4. Smelly Heaters

When the anode corrodes and reacts with water it produces a rotten egg smell. Magnesium rods produce more smell than aluminum rods. A zinc anode is the only rod that does not produce a rotten egg smell. Be that as it may, the zinc rod is not durable at all, and water heaters are mostly placed in an enclosed corner of the house. In hindsight, the smell can be easily ignored as it does not interfere with the working of the heater.

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5. Low or High Voltage

Aluminum rods are slow to work since they give away their electron slowly. As a result, they produce low voltage. Magnesium rods continue to carry out electrolysis faster than aluminum. They produce higher voltage and increase the efficiency of the tank-based water heater.

6. Installation Time:

Magnesium rods come with screw-on caps whereas the aluminum rods do not have any specifications. Most people, therefore, prefer the magnesium rods over aluminum rods when they are doing a replacement on their own. Most plumbers also prefer magnesium rods as they are easy to handle and save time.

7. Reduce Chlorine Levels

Chlorinated water is not suitable for tank-based water heaters. Magnesium anodes reduce the alkaline levels in the water making the water heater last for a long time. Chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm) are considered safe however if they increase from these levels, they can quickly become dangerous to your health.

8. Sulfate Safety

If you live in an area where the water has a large amount of sulfate aluminum rods are the best option for you. When there are a lot of sulfates in the water, it gets readily contaminated. Aluminum converts the sulfates into hydrogen sulfite reducing the levels of contamination in water.

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9. Hard Water- Aluminum Rod

Aluminum rods are the best choice for areas in which hard water is available. Aluminum reacts with hard water and produces less reactive compounds. As a result, the rate of corrosion is reduced and the anode rod lasts for much longer as compared to magnesium rods.

10. Soft Water -Magnesium Rod

Magnesium rods are usually a better choice for soft water areas. Since magnesium is mild and unreactive with most other compounds in the periodic table it will not contaminate the soft water. Moreover, the speed of corrosion of the magnesium rod will be reduced, giving you a lasting water heater performance.

Aluminum vs Magnesium Water Heaters? Which one is Best?


According to water heater picks , after comparing and contrasting the two materials for their durability, viability and affordability the final verdict goes in favor of magnesium. As magnesium does not form sediments at the bottom of the tank, it does not destroy the whole water heater. Aluminum rods are prone to corrosion from the get-go. Most people do not know when to replace their anode rods. In consequence, the rod keeps corroding throughout the year without anyone knowing it. When the anode rod is completely kaput it starts causing problems in the water heating process. When you are most likely to look into the problem causing your water heater to malfunction, it will be too late. The whole body of the water heater would have been ruined due to the corrosion of the aluminum rod. Magnesium rods are easy to install, produce higher voltage and reduce the chlorine levels in the water tank. Magnesium is then the best choice for an anode in a tank-based water heating system.

Aluminum vs Magnesium Water Heaters? Which one is Best?