Corrosion Control in Household Systems

If the main cause of water corrosiveness is low pH (acidity), the water can be neutralized using special filters containing such materials as calcium carbonate (calcite) or magnesium oxide (magnesia). These filters serve also as mechanical filters and therefore must be backwashed periodically with some additional active material added. Another method of neutralization requires the addition of sodium carbonate (soda ash) into the system. This should be injected ahead of the pressure tank. If chlorination is used, this solution can be mixed with the chlorine solution.

One has to keep in mind that addition of soda ash may slightly increase sodium level in the drinking water, and calcium carbonate filters will increase hardness and alkalinity.

A different approach to the control of corrosion is the injection of certain chemicals, such as polyphosphates and silicates, to create protective films on plumbing components. Selection of noncorrosive plumbing materials, like plastic or polyvinyl chloride, will help. Since corrosion increases with elevated temperatures, water heaters should be set only as high as necessary and temperatures above 30°C are not recommended.

Corrosion associated with other chemicals like hydrogen sulfide and dissolved oxygen must be handled differently. For example, hydrogen sulfide can be treated by activated carbon filtration or chlorination.