Water Heater Corrosion: How Do Anodes Work?

A water heater.

When it comes to preventing water heater corrosion, the part of the water heater that plays the biggest role in this process is the anode. In some cases, this piece of equipment is referred to as the sacrificial anode. This is because it essentially sacrifices itself for the good of the water heater over time. Read on to learn about the basics of the water heater anode and how it works.

Water Heater Anode

A water heater anode is a piece of wire that has a magnesium or aluminum coating. This narrow rod is then inserted into the top of the water heater and down into the area where the water will be heated.

During regular use, several minerals are introduced into the water, and small electrical currents will pass through these minerals. Without the anode, the electric currents would pass through the outside of the water heater tank. When this happens in high temperatures, it essentially makes the metal in the tank start to corrode. The electric current will make the tank start to rust and it will eventually deteriorate. With the water heater anode in place, the electric current will pass through the anode instead of the tank itself.


When the electric current passes through the anode, it will cause the magnesium or the aluminum to deteriorate. Most of the time, this happens at a relatively slow pace. In most residential water heaters, a single anode will be expected to last for approximately six years. In some water heaters, manufacturers actually put in two anodes so that they can extend the life to 12 years. Some commercial water heaters will actually have several anodes in them so that they can handle more water output.

In some cases, the anode will deteriorate very quickly. This generally occurs when the water heater is processing soft water that has a great deal of salt content in it. Sometimes, this can cause the anode to deteriorate in as little as 6 months.


When the anode is deteriorated, that does not necessarily mean that it has to make your water heater nonfunctional. You can actually replace the anode at your discretion. You can simply unscrew the anode out of the top of the tank and take it out at any point. You can then buy a new anode to fit into the tank and get additional life out of your water heater.

This means that you need to periodically pull out the anode and check it to make sure that it is not completely deteriorated. If you allow the anode to deteriorate, the electric current will start to pass through the outer shell of the water heater tank. This will ultimately result in the destruction of the tank, and you will then have to purchase a completely new unit.