Solving disinfection byproducts led to unintended consequences

Controlling chlorine-based carcinogens in drinking water may have helped set the stage for lead issues now surfacing nationwide, water experts say.

The recent lead crisis in Flint, Michigan, and in Washington, D.C. in the early 2000s was, in part, the unintended consequence of federal rules that kicked in during the late 1990s and strengthened in the mid 2000s to lessen the byproducts of chlorine and other disinfectants linked with increased lifetime cancer risk.

Some methods used to control the byproducts of disinfection can result in more corrosive water. To save money, many systems just added ammonia to the mix, to create chloramines — a group of chemicals with its own host of potentially irritating problems.

“It was these warring regulations,” said Sheldon Masters, senior environmental engineer at Corona Environmental Consulting in Philadelphia. “By meeting the disinfection byproduct rule, you created a problem meeting the lead and copper rule.”

The lead issues emerging nationwide underscore the complex trade offs water operators often make between short-term and long-term health risks. Sometimes, solving a long-term risk can create a more acute risk, environmental engineers say, and as communities tap lower quality water supplies to meet demand, getting the chemistry right at the treatment plant is crucial in avoiding unhealthy pitfalls.

"I think the big issue is how the water's treated," Thomas Waite, an environmental engineer at Florida Institute of Technology, said of how to prevent lead contamination from corrosion. "It really falls on the treatment plants themselves to try to keep a handle on it. By that, I mean regulating the pH of the water. Treatment plants have really got to be serious about the corrosion concept, meaning pH going outside of the plant."