How Water Heater Rust Prevention Fails And What You Can Do About It

If you start to see rust flakes or reddish-brown water coming out of your hot water faucets, then there is a good chance that corrosion has started to form within the water tank itself. Most water tanks are protected from corrosion, but the protective measures may sometimes fail. Keep reading to learn how this failure may occur and how you can attend to the problem.

How Are Water Tanks Protected From Corrosion?

Hot water tanks heat up a great deal of hot water over time and hold this water until you use it. The main tank is made out of steel so the appliance can function over a long period of time without succumbing to wear and tear. However, steel will corrode and form a layer of rust, and the conditions within the tank are ideal when it comes to rust formation. The acidity of the water, the high levels of heat, the dissolved oxygen within the water, and the mineral content in the fluid all encourage rust to build. To protect the tank from corrosion, the inside of the tank is covered with a layer of glass or porcelain enamel. This coating protects the majority of the steel in the tank from coming into contact with water. 

The glass coating will typically not cover all of the metal surfaces in the water heater. Burners and heating elements as well as hardware around outlet openings and the outlet openings themselves will be lined with exposed metal. Also, small cracks can form in the glass coating over time and expose a part of the tank. To help keep exposed areas of steel from forming rust, the tank will be fitted with something called a sacrificial anode. The anode is a piece of metal that will actively corrode and interact with the water on an electrochemical level. This way, the anode will disintegrate instead of the water tank. 

How Do You Check For Rust Protection Failures?

In some cases, the corrosion protection features of the tank will fail. This will happen over time as the water tank is used continually for years on end. As the tank ages, more and more of the porcelain coating will crack and expose the steel underneath. When large amounts of the steel are exposed, the tank will typically form rust across the tank. You can check for this issue by looking at the sides of the tank itself. As rust builds, you will start to see rust spots starting to develop on the exterior of the tank. Specifically, rust will protrude through the enamel paint that covers the outside of the appliance. 

Corrosion protection will also fail as the sacrificial metal anode inside of the tank breaks down and fully corrodes over time. The anode can be checked for deterioration by pulling it out of the tank. You will see a cap protruding from the top of the tank where the anode sits. Unscrew the cap and pull the anode up and out of the tank. If you only see a thin wire left behind or if the anode is extremely pitted with many holes, then the anode is in need of replacement.

How Do You Fix The Problem?

If rust spots are starting to work their way through the water heater due to the deterioration of the glass lining, then your appliance will begin to leak as rust disintegrates a relatively large area of the steel. You should invest in a new water heater before this happens.

If you do not see rust spots in the water heater, but the anode has deteriorated, then you should replace the anode. There are several different types of anodes you can buy, and some varieties are made out of pure aluminum. These anodes can wear away relatively quickly, so opt for a variety that is made from a combination of zinc and aluminum. This type of product will last longer and keep your water heater protected from rust for a longer period of time. For more assistance, contact a plumber.


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