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The authors investigated factors influencing the occurrence of dissolved lead in tap water using different sampling protocols. The principal factor affecting the concentration of dissolved lead at the distribution system taps was the length of lead service lines (LSLs). However, dissolved lead levels in first‐litre samples were also associated with lead particles being trapped in the aerator. Collecting the first‐litre sample after 30 min of stagnation provided a good estimate of lead concentration in premise plumbing and LSLs, even though it could sometimes underestimate peak lead concentrations in the LSLs. Also it gives mean exposure estimates close to that obtained using random daytime sampling. Lead levels remained relatively high in flushed samples despite short (26‐s) contact time between the water and lead pipe, illustrating high rates of mass transfer.