Most of the U.S. public is well educated about the effects of lead on the human body-particularly its effects on young children. With the ongoing Washington, DC, lead saga continually in our nation's news, it is only appropriate to discuss solutions to lead in drinking water. But first, let's look at how it gets there.
The Washington, DC, lead problems are most likely a result of a change in water chemistry-one that could take place in a number of other cities throughout the U.S., as well. (In some cases, it may already be occurring.) The Washington, DC, situation may also be a case of a utility's best intentions with respect to one water quality parameter negatively affecting another. In an effort to reduce the levels of disinfection byproducts (DBPs) that can accompany chlorine disinfection in certain scenarios, the DC Water and Sewer Authority (WASA) switched to chloramine disinfection in Nov. 2000 for secondary disinfection (distribution system protection against pathogens). The switch was a response to the regulation of DBPs at very low levels in drinking water due to suspected carcinogenic effects. Prior to the switch, DC water was disinfected using free-chlorine (elemental chlorine), which reacts to form a lead oxide that can coat surfaces. For a long time, such an oxide coating may have been responsible for reduced leaching rates and binding of lead in the water system.