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Trace contaminants have been shown to accumulate in solids found in drinking water distribution systems and can potentially be released to the consumer—s tap water. The objective of this study was to identify and evaluate the source of high arsenic in consumers— tap water at a small drinking water system and assess the effect of the installation of a treatment system for iron/arsenic removal. Before treatment, water samples collected from home taps showed high arsenic concentrations (as high as 299 μg/L) that were attributable to iron solids found in the distribution system. In 29% of the tap water samples, arsenic concentrations in first‐draw water samples were greater than arsenic levels in water entering the distribution system. Color measurements proved to be good predictors of arsenic and iron levels in the tap water, and turbidity was a relatively poor predictive measurement.

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The US Environmental Protection Agency's Office of Research and Development designed, fabricated, and installed four pipe rigs in Flint, Mich., to help the city optimize corrosion control. The lead service line (LSL) pipe loops were constructed of polyvinyl chloride pipe and fittings and welded steel channel frames. Each pipe rig consisted of four approximately 4 ft-long sections of 0.75 in. inside diameter lead pipe that were excavated from homes fed by the Flint distribution system. The rigs were operated on a set daily on/off schedule such that a specified amount of water passed through each pipe using a solenoid valve-operated timer system. Solenoid problems resulted in sporadic and enhanced daily flow volume (but no flow rate changes) that prevented restabilization of pipe scales. Lead levels were relatively sporadic and statistically different during this period. After the solenoids were replaced, the lead pipe rigs were successfully conditioned, and lead release with consistent influent water chemistry became relatively stable. Average lead levels across all 16 loops ranged between approximately 2 and 5 μg/L after the solenoid replacement. The lead results were consistent with levels measured from LSLs from homes in the city during sequential sampling efforts.