Compared to other major residential appliances, water heaters are subject to an incredible amount of wear and strain. Not only do they have to withstand the fatigue inducing effects of constantly cycling between hot and cold states, but they also have to be built tough enough to resist damage as the result of near constant exposure to water.

As tough as water heaters are, it should come as no surprise that they still succumb to problems as time goes on. A surprising amount of water heater problems have to do with worn out anode rods. If you would like to improve your understanding of water heater mechanics and troubleshooting, read on. This article will introduce you to the crucial function of the component known as the anode rod.


Of the two threats mentioned above — heat and water — the latter represents a much more pressing threat to the structural stability of a water heater. Because the inner walls of the water heater remain in contact with water for years on end, oxidation and corrosion present ongoing threats. Oxidation acts to remove electrons from the steel walls of the tank.

This removal in turn leads to the formation of hydroxide ions — the preliminary step in the process of rust and corrosion formation. Once set in motion, the negative effects of corrosion will quickly snowball, literally eating away at the tank walls. Eventually, in the absence of professional intervention, the walls will become so weak that they fail, leading to highly dangerous ruptures.


All water heaters contain a feature designed especially to increase their resistance to the forces of corrosion: the anode rod. Also sometimes referred to as the sacrificial rod, the anode rod protects your tank by making itself a more attractive target for corrosion. As long as enough of the anode rod remains, the forces of corrosion will essentially ignore the walls of your tank.

Problems ensue once the anode has been completely or nearly completely eaten away by corrosion. Eventually there will be nothing left but the naked steel shaft at the center of the anode rod. Should things be allowed to get to this point, corrosion will renew its attack on your tank. To prevent this, a fresh anode rod must be installed.


Now that you understand the basic function of an anode rod, you may be curious about how this component works. What, after all, makes it more capable of attracting corrosion than the steel walls of your tank? The answer has to do with the metals used to compose an anode rod.

So-called sacrificial metals — magnesium, aluminum, and zinc being three of the most common — make up an anode rod. The electrons of these metals are bound much more loosely than those as steel, making them easier for corrosive salts and acids to bond with. The chemical process at the heart of corrosion will thus drive it to spend itself on the anode rod, causing it to literally disappear in the process.


A typical anode rod contains a great enough amount of sacrificial metals to protect your tank for approximately four or five years. At that point, the rod will have all but disappeared. The precise timing will depend on the chemical makeup of your water supply, as well as how heavily the tank gets used.

To determine the state of the anode rod, it must be removed from the tank — a process that should always be left to an expert. Homeowners who attempt this maintenance task on their own place themselves at serious risk of burns. Not only that, but if the rod is not correctly reinstalled, it may lead to further problems for your water heater.

If you can't remember the last time you had your anode rod inspected or replaced, please don't hesitate to contact the experts at C B Lucas Heating & Air Conditioning for a professional maintenance evaluation.