How Larger Lead Scale Particles are Likely to Move in Service Lines

If lead service lines are present, small lead-containing particles often are observed in drinking water. Because such particles inevitably differ in size, if many small particles are observed, there likely are a few larger ones as well. This work examined the potential movement of such larger particles using a mathematical model for particle transport in pipes. This model suggested that lead scale particles in the size range $20–400\text{-}\mathrm{\mu m}$, if they exist, would move toward the home or serviced location along the bottom inside surface of the pipe (i.e., as bed load) under typical flow conditions ($u=0.43\mathrm{m}/\mathrm{s}$). These bed load particles could collect at obstructions, or in a home’s basement. According to the model, high-rate flushing ($u=0.95\mathrm{m}/\mathrm{s}$) at the hose bib will fully suspend these particles in horizontal pipes, ideally removing them. This research supports the practice of high-rate flushing, for example, at the hose bib, to remove persistent lead particles after service line replacement.