The objective of this project was to study the elemental composition of mineral scale in aged iron and steel water distribution system pipes. Pipe samples were obtained from a small Midwestern town which replaced the entire water distribution system. The aged system was constructed in 1935, and had been in continuous service since that time. The water in contact with the distribution system pipes was an untreated groundwater. This system was chosen for study for several reasons: the entire system dated from one period of time and was composed mainly of one material, as opposed to most systems in large cities which have been constructed over a many year period; the town used an untreated water supply with high concentrations of some elements known to cause scaling; and, the town water system had been poorly maintained and was expected to be very corroded, due to age and lack of care. Pipe samples were obtained after the pipes had been removed from the ground and allowed to dry. Pipes were analyzed using: optical microscopy for measuring scale thickness, for visually determining the integrity of the scale, and for visually identifying minerals by color and form; x-ray diffraction for identifying crystalline compounds found in mineral scales on the pipes; and, scanning electron microscopy for taking high magnification photographs and also for elemental scans.