Data visualization by Ben Vankat. Research by Natasha Gilbert.

An EPA survey released in 2021 tested 5,034 public water systems across the U.S. and found potentially unsafe levels of manganese — where neurological effects may occur — in 106, or 2.1%, of them. The EPA advises consuming no more than 300 micrograms per liter each day over a lifetime to protect people’s health. About 650 water systems, or 13%, failed to meet the EPA’s aesthetic standards (for taste and appearance), not to exceed 50 micrograms per liter.

Click on a colored zip code to see the result of a system’s sole well or facility tested or the one with the highest concentration.

Source: U.S. Environmental Protection Agency.

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