Using monochloramines to disinfect drinking water: the effects it has on lead content

Over the past ten years, several U.S. cities have switched from using free chlorine to chloramines to disinfect drinking water. Coincident with this shift have been reports by some water districts of lead (Pb) levels in drinking water that exceed the action limit of 15ppb set by the EPA. In this paper, a study was conducted on a water district that utilizes monochloramines to disinfect drinking water. The purpose of this research was to determine the Pb content of drinking water treated in this district. Water samples were collected both from homes with and from homes without Pb plumbing. The water samples were analyzed for Pb content using graphite furnace atomic absorption spectrophotometry. Samples obtained from homes without Pb plumbing had a Pb concentration range of 10.7 ppb − 20.3 ppb (average = 15.9 ppb), whereas samples obtained from homes with Pb plumbing had a Pb concentration range of 20.4 ppb − 73.9 ppb (average = 29.0 ppb). The average Pb concentrations for both types of homes were above the EPA action limit of 15ppb. The most plausible explanation for this is leaching of Pb from the water distribution system caused by the water treatment plants' use of monochloramines to disinfect water.