It took three years for officials to notice lead was seeping into the city's drinking water.

Missouri regulators had given the green light in 2014 for Trenton to start adding monochloramine to its drinking water to disinfect it without the harmful byproducts of chlorine.

But by 2017, the city noticed something alarming.

Lead levels in drinking water in the northwest Missouri town — population 5,609 — had spiked.