The recent lead contamination problem in Flint, Mich., was not the first time there has been a severe public health issue caused by a tainted water supply. As recently as February 2016, officials in Ithaca, N.Y., distributed bottled water to children after lead levels that were hundreds of times higher than recommended were detected in drinking water in a local school. Similar cases have come to light in Portland, Ore., Newark, N.J., and in Baltimore, Md.
As in Flint, many of the problems in these other cases were due to the corrosion of pipes that carried water to people’s homes, and, as in Flint, among the main culprits were copper and lead. But the water we drink everyday already contains small amounts of lead and copper (along with other metals), so how do we know when their amounts are too high to make water unsafe to drink?