Effects of blending on total copper release in distribution systems

The use of alternative source waters has become common because of limited resources, increased demand, and regulatory constraints, However, these practices can create blending problems in distribution systems and lead to release of corrosion products. This work attempted to correlate varying water quality and associated confounding effects to copper release using data from a field study of pilot systems distributing finished waters produced from groundwater, surface water, and saline sources. Finished groundwater, surface water, and desalted seawater were characterized by high alkalinity, sulfates, and chlorides, respectively. Finished waters with high alkalinity and low pH (both of which are common in conventionally treated groundwaters) released more total copper than other waters. Because water source and treatment processes can significantly affect total copper release, water providers should undertake preventive measures such as water quality adjustment and/or corrosion inhibitor addition. The nonlinear regression copper release model presented can be used to develop more fundamental strategies to mitigate copper corrosion and distribution water quality deterioration. - MPM.