Marc Edwards, a professor in the engineering department at Virginia Tech who has been involved in many water investigations, said lead most commonly gets into drinking water through lead pipes that run from water mains into homes. There are also possible sources within homes, including lead solder on pipes or brass fixtures with high lead content.
Generally, he said, those pipes and fixtures begin to shed lead when there are changes in the water supply that make the water more corrosive, causing the lead to leach from the pipes.
The lead pipes that run into the homes, known as service lines, are common in many older cities around the United States, affecting as many as 11 million homes, he said. Lead has been used in pipes that deliver water since ancient times, he noted, because it is long lasting and flexible. “Other than poisoning and killing people, it’s a great plumbing material,” he said. Many cities used to require their use, including Newark.
It has yet to be conclusively proved why the water became more corrosive, Mr. Olson said, but a city contractor noted that in 2015 Newark had tried to address a different issue with contaminants and “they adjusted their treatment” in ways that made the water more acidic.
“This change in water chemistry may have been responsible for Newark levels being so high now,” he said. “It’s an echo of Flint,” he said, referring to the lead contamination in that city’s water, which jumped when Flint chose a different, cheaper water source that was more corrosive, without taking action to counteract the effect of the more corrosive water.
The group’s lawsuit asks the court to order the city to treat the water with corrosion inhibitors, and to replace the old lead service lines. There is a hearing related to the lawsuit in Newark federal court on Thursday.
Nick Corasaniti reported from Newark, and Corey Kilgannon and John Schwartz from New York.