Role of natural organic matter and hardn

Lead release into drinking water from lead service lines, lead containing solder, and plumbing fixtures continues to challenge many utilities. Corrosion inhibitors such as orthophosphate are often added to mitigate lead release, but their use may not be feasible for all utilities. This study aims to investigate alternative strategies to minimize lead release, focusing on the roles of natural organic matter (NOM) removal and hardness adjustment. Using a two-level fractional factorial design, the experiment followed a 'dump and fill' protocol with new lead and copper pipes exhibiting an external galvanic connection. The results indicated that the presence of Suwannee River NOM significantly increased dissolved lead release in water samples (average concentrations of 140 μg L−1 without NOM and 2460 μg L−1 with NOM). Fluorescence excitation emission matrices further suggested that dissolved lead release correlated with decreases in humic-like peaks, potentially due to the quenching effect of lead–NOM complexation. While hardness and dissolved inorganic carbon had non-significant effects on lead release, increased DIC concentration was associated with higher galvanic current. pH adjustments also showed significant differences in total lead release, indicating complex interactions between chemical parameters influencing lead solubility.