AWWA JAW71675

Despite the documented inefficacy of the calcium carbonate approach to corrosion control, adjustment of calcium carbonate remains the dominant corrosion control strategy. Many utilities still significantly increase alkalinity (with limited or no success) or try to operate at much lower pH values than necessary, both as a means of lead and copper control. Consistent high pH is the main variable controlling release of lead and copper at customer taps. The extent to which pH can be raised must be carefully evaluated on the basis of site-specific conditions. The San Francisco Public Utilities Commission (SFPUC) case profiled here demonstrates that maintaining a high pH is a more appropriate corrosion control treatment to comply with the Lead and Copper Rule (LCR) than adjusting the Langelier saturation index or augmenting alkalinity. The combination of water quality and distribution system conditions at SFPUC is such that a switch from free chlorine to chloramine did not affect lead and copper release or LCR compliance. Includes 49 references, tables, figures.