"An investigation was conducted to determine the causes of rapid pitting failure of galvanized steel pipe used in consumer plumbing systems. The presence of copper in water and the character of the galvanized steel pipe were factors examined in detail. Pipe manufactured in Korea, Australia, and in the United States was compared for pipe structure and zinc coating. The pipe manufactured in Korea by electrical resistance welding had a pronounced weld seam, whereas U.S. and Australian pipes manufactured with buttwelding had only small or nonexistent seams. Furthermore, the zinc coating on the Korean pipe failed to meet the weight of coating standard (1.8 oz/ft2) in 11 of 14 samples. Examination of the iron/zinc interface on the Korean pipe revealed possible sites of poor adhesion of the coating to the base metal. In pilot testing, increasing copper concentrations (from 0.0 to 5.0 mg/L) produced increased corrosion activity on the pipe surface, as measured by greater deposition of scale, calcium, iron, zinc, and copper. Also, the ratio of iron surface to zinc surface area increased. Other factors such as the mode of exposure and the addition of citrate had no measurable Impact. The corrosion activity measured by scale formation was greatest on the Korean pipe, followed by the U.S. and Australian. Rapid pitting of the sort observed In several southern California homes did not occur under any of the conditions tested."