Electrochemical nature of lead contamination

Because the minimization of lead pickup by water quality modification has not been predictable, one of the objectives of this work was to provide a basis for such predictions. There are three major situations in which lead is in contact with potable water: lead pipes, lead-based solders, and brass and bronze fixtures. For lead pipes, the mechanism of corrosion is primarily that of establishing a concentration cell on the lead surface that results in electron being transferred from one point on the surface to another. Increasing the pH or minimizing the dissolved oxygen or chlorine residual is an effective means of reducing the corrosion rate. For solders and alloys, the galvanic corrosion is due to the direct contact of the dissimilar metals. Water quality has very little effect on this type of corrosion. The author comments that it is hoped that a continuous decrease in lead violations will be seen as the ban on lead solders takes effect and the exposed lead surfaces are removed by corrosion.