The engineer who uncovered the lead crisis in Flint, Michigan – where the water was toxic enough to give kids  brain damage – doesn't even live in Michigan.

His name is Marc Edwards, and he teaches engineering at Virginia Tech, more than 500 miles away. Marc started investigating water pollution in Flint last August. But he got his start more than a decade ago, in Washington, DC, when he discovered high levels of lead in that city's water.

In DC no one would listen to him. He lost lucrative contracts and spent thousands of dollars – of his own money – sampling the water to prove it was contaminated even when the government insisted it was safe. In the end, he prevailed and the water was cleaned up. But not before thousands of kids were exposed to dangerously high amounts of lead.

This week, we talk to Edwards about his crusade to make our water safe. Getting the science right turned out to be just the beginning of a fight. The harder part was figuring out how to convince people he was right.