Approximately 0.1 % of 25000 leaded brass stop valves failed in potable water service in western Canada. All failures were brittle fractures in the reduced section of the barb at the shoulder. Increasing the wall thickness at that point stopped the failures. Failure was initiated in small but heavily work-hardened bands on the interior walls underneath patches of corrosion product. These appear to be due to microbial action. Crack growth occurred only in the reduced section by a variety of mechanisms including dezincification, anodic dissolution, corrosion fatigue, and stress corrosion cracking. Anomalous distribution of lead and zinc on the fractures was noted. The former was due to the corrosive breakdown of the lead particles in the brass. The low number of failures experienced indicated that the fracture process was complex enough to require that many conditional requirements be met to produce fracture.