Corrosion refers to the process where metals become oxidized due to some substance(s) in their environment.

Many substances contribute to the corrosion of steel or copper pipes. Factors that increase the corrosion of steel or copper pipes include low pH levels, high oxygen levels in the water, high pressure and temperature of water flowing through the pipes, certain concentrations of dissolved minerals, and bacterial buildup.

It is not known to what degree certain acids contribute to corrosion, but high (basic) pH values tend to prevent corrosion and low (acidic) pH levels increase the rate of corrosion. For example, in copper pipes, high pH (> 8) causes a copper oxide film to coat the pipe walls which protects the pipe from corrosion.