Corrosion, or the process of gradual degradation of materials due to the action of environmental factors, is a serious threat to any type of water-bearing system. Corrosion of water installations may have the form of a chemical reaction, electrochemical reaction, microbiological processes or physical processes leading to damage of structural materials. The metal oxides formed as a consequence of corrosion reactions penetrate into the system, contaminating water (rusty water). The risk of corrosive changes is present in both installations with hot water and in cooling systems. Depending on whether we are dealing with a heating, steam (water-steam boiler) or cooling system or a system supplying drinking water, different types of protective measures should be applied – corrosion inhibitors.