Every house has its own sounds. The sump pump cycling after a heavy rain, or the ductwork snapping as it heats up and expands, or that unexplained cracking we hear late at night when we are all alone.

Flint, Michigan, made headlines in 2015 when tests revealed dangerously high lead levels in its drinking water. The city had switched its water supply to the Flint River a year earlier, and corrosive ...