Drawbacks of Using an Aluminum Water Heater Anode Rod

Repairman checking a water heater.

An aluminum water heater anode rod is placed into a water heater to prevent corrosion. In the same way that ships use sacrificial rods to protect the metal of the hull, an anode rod attracts the corrosion and keep the rust and corroding elements away from the water tank itself. While there are a few advantages of anode rods, you should be aware of the disadvantages too.

How the Anode Rod Works

Anode rods can be made of aluminum or magnesium. They work by electrolysis which deteriorates the rod instead of the metal of the tank. If the rod itself is completely deteriorated, then the tank will begin to corrode. For many homeowners, this is the first sign that they have a problem since these rods are not always situated in a way that makes it easy to check on their condition. There are some situated on the top of the water heater. To find and evaluate this type look for a plug with a fitting that is screwed into the top of the tank. The anode rod is suspended from that fitting into the tank.

Anode Rod Inspection

Manufacturers tell customers to check the anode rod on every 2 to 4 years. The problem is that it takes a certain amount of work to replace one even if you know it is bad. Sometimes it is less expensive to replace the entire tank rather than the rod because of the labor cost involved. This is especially true if the rod is difficult to remove because of its fitting or a buildup on the rod.

Tank Protection

The other problem is that an aluminum anode rod does not protect the tank completely. Occasionally a plumber sees a tank that is rusted through that still has much of the anode rod intact. There are several possible reasons for this. One is that if a house has a water softener, then it can hasten the corrosion of the anode rod.

Magnesium vs. Aluminum Rods

Many plumbers prefer magnesium anodes because they produce a stronger current making them more effective at keeping the water tank from corroding. Aluminum rods collect a buildup of corrosive materials that harden and make taking them out for inspection or replacement a challenge. Magnesium may react with bacteria causing a sulfurous smell. Aluminum rods don’t have this problem as often.

Aluminum in the Water

Some plumbers say that aluminum anode rods are not safe because they put aluminum in your water supply. There are some clinical studies that suggest that aluminum might be a contributing factor in Alzheimer’s disease. It should be noted that most of these studies focused on the aluminum added by water treatment plants.

Alternatives to an Aluminum Anode Rod

An anode rod made of a mixture of aluminum and zinc appears to prevent odors since the zinc changes the chemical composition of the water. Another alternative is an electrical anode rod. This kind of anode rod produces an electrical charge in the water instead of having a chemical reaction.