Too many water samples above that level is a red flag for utilities, a sign that they may have a broader lead problem.
Virginia Tech researcher Marc Edwards, who leads the team documenting Flint’s water problems, called the new results the “beginning of the end,” a turning point in the city’s saga with corrosive water.
But it came with a caveat: “Certainly, Flint residents should continue using the bottled water and filters,” he warned.
That’s, in part, because the EPA action level – 15 parts per billion of lead in the water – is not a threshold for public health, so a reading below that number doesn’t mean the water is safe.
Public officials and school administrators often reference that level to assuage fears about lead in the water.
But Jeff Cohen, who was on the EPA team that decided on that number, said linking it to a threshold for public health is a “misunderstanding.”
“The goal of the rule is zero lead in drinking water,” he said.
The EPA’s action level isn’t based on medical research. No amount of lead is known to be safe.
“It was never designed to identify a safe level of lead in drinking water,” Cohen told NPR.
He said the number was simply what water utilities told the EPA they could manage with treatment back in the late 1980s, when the EPA’s Lead and Copper Rule was drafted.
“It was based on the little data available at that time, from water utilities in the U.S. that had installed different levels of corrosion control treatment,” he said.
When there is lead in the water, most of it comes from underground service lines that carry water to more than 6 million homes, according to water utility estimates. Smaller amounts of lead can also be found in home plumbing systems such as in solder and fittings.
Wherever lead exists, …