Corrosion of pipes for conveying drinking water in Hong Kong: mechanisms and controlling strategies

A drinking water distribution system (DWDS) ensures access to safe water and provides the basis for city life. However, the pipes in DWDSs are threatened by corrosion externally and internally. This paper critically reviews the mechanisms and types of corrosion in pipes for drinking water, followed by an outline of the related controlling strategies. Special focus is accorded to pipes under the soil environment near coastal areas subjected to seawater intrusion. The corrosion that happens internally (erosion-corrosion, microbially influenced corrosion, and other ions) or those that occur externally (corrosive soils, dissimilar metals, stray current, coating damage, and microbial-influenced corrosion) eventually leads to electrolytic corrosion. It is found that soft soil (partially due to seawater intrusion) is a significant threat to corrosion in DWDSs because it is corrosive and may cause external stress problems for existing DWDSs. Some suggestions and controlling strategies are proposed in the current review.