The federal Ground Water Rule may require some water utilities that do not use disinfection to begin doing so. A common method of disinfection is to add chlorine to the water. A study was performed to investigate the corrosive effects of chlorine in drinking water systems out of concern for staying in compliance with the corrosion control stipulations of the Lead and Copper Rule. Comparative corrosivity experiments using pipe loops were performed at two test sites. In this study, iron appears to be the most affected by free chlorine addition, followed by copper, followed by lead, which may or may not experience increased corrosion.Elevating the pH of the water at one site (originally at a pH of 7.8, 140 mg/L as calcium carbonate [CaCO 3 ] total alkalinity, 6 mg/L dissolved oxygen) was beneficial in counteracting the corrosive effect of chlorinated water on iron. However, in this case, the elevation of pH was not beneficial in controlling corrosion of lead or copper. Adding orthophosphate decreased corrosion of lead and iron in contact with chlorinated water at the other site (original pH of 7.4, 290 mg/L as CaCO 3 total alkalinity, 11 mg/L dissolved oxygen). However, copper corrosion appeared to reach an increased level in the long term.