Opferanode Warmwasserspeicher

What is a sacrificial anode ?

Dealing with sacrificial anodes is essential, if you own a storage tank and therefore are responsible for it yourself. Few are even aware of the existence of sacrificial anodes and their function remains a mystery to many. In short: The protective anode sacrifices itself for the "more noble" metal in order to protect it from corrosion. It must be electrically connected (e.g.in the storage tank). 
Not only do we manufacture sacrificial anodes for storage tanks ourselves, we also explain below what sacrificial anodes are, how they work and how you can benefit from them.

Sacrificial anodes for storage tanks are made of magnesium. We produce them in form of rod anodes or chain anodes. Anodes protect the enamelled steel inside of the storage tank against corrosion. Steel consists to a large extent of iron, which is the noble metal compared to magnesium.   

Every enameled storage tank has production-related defects. The enamel works as a protective layer for the wall of the storage tank. There are additional defects resulting from changing temperature conditions and associated expansion and contraction. These defects are subsceptible for corrosion.

In order to protect your boiler from corrosion, the magnesium anode sacrifices itself and corrodes instead of the storage tank wall. The magnesium of the protective anode (less noble metal) dissolves in this process and settles on the defects of the enamelled layer. 

How does a sacrificial anode work?

Different metals are connected to each other via a galvanic cell. The anode, being the less noble metal, sacrifices itself to the more noble metal (cathode). To prevent rust, the sacrificial anode uses the electrical potential of different metals. 

In order for this reaction to take place, the different metals have to be electrically connected to each other. In this case a galvanic element is created by the water and the two different metals inside of the storage tank. The metal with the lower voltage (Anode- magnesium anode) dissolves in the water (elektrolyte). The dissolving magnesium wanders through the water to the metal with the higher voltage (cathode-enamelled storage tank wall). 

How long does a sacrificial anode last?

In order to ensure the best possible protection we recommend checking the condition of the anode after your new storage tank is in use for a year. You should replace it after two years at the latest. After that, the anode replacement can be adjusted depending on the condition of the protective anode. Furthermore, the maintenance specifications of the manufacturer should be observed.   

Where are protective anodes used?

Mainly sacrificial anodes are used in shipping and inside of storage tanks. But there are many other areas in which sacrificial anodes are used, such as pipelines, liquid gas tanks, tank farms, gas storage systems, combined heat and power plants, cooling systems for machines, swimming pools and much more. 

How much does a magnesium anode cost?

On average, sacrificial anodes cost between 30 and 50 euros (25-45 GBP). Magnesium anodes directly from the manufacturer usually cost many times more. On various platforms sacrificial anodes are sometimes offered for less than 10 euros. Caution is advised as quality (cheap cast anodes) and service are often forgone. After all, buying a new storage tank can cost several thousand euros.   


Sacrificial anodes protect your storage tank from corrosion. High costs due to water damage can be avoided easily by using protective anodes. Corrosion phenomena cannot be reversed. The storage tank usually needs to be replaced, once the storage tank has rusted through.   

Regular replacement of the anode is important to protect your storage tank from corrosion in long term. 

If there are any questions left and you are not sure which magnesium anode you need, don't hesitate to contact us.