Prenter Hollow, W.Va. is a tight-knit community that has battled water and health problems for years. Robert Johnson for Business Insider With massive coal reserves acting as a natural charcoal filter, West Virginia used to be famous for its well and spring water.

"We had the best darn water in the world," Prenter Hollow, W.Va. resident Maria Lambert said when we visited her home in mid-January, "but that all changed, didn't it?"

It took years for the Lamberts and their neighbors to accept that their water may have been contaminated by nearby mountaintop removal coal mining. Not only was mining taking away their charcoal filter, but it also threatened to contaminate their water supply with toxic chemicals.

In a 2009 lawsuit, locals blamed broad health problems including elevated cancer, surgery, and mortality rates on mining activity. They received compensation in a 2012 out-of-court settlement with Alpha Natural Resources, which had bought the suspect mine from original owner Massey Energy. (Alpha did not respond to a request for comment on this story.)

It's hard to say exactly how much Prenter suffered, and no one knows how common these problems are. Coal, which provides around a quarter of America's consumer energy, is so important to the local economy that people try not to ask many questions. Still, locals seem resigned to negative health effects.

The people of Prenter eventually got off their well water and onto city tap water. In January, however, their supply was contaminated by the Elk River chemical spill, forcing them to drink bottled water for a week and leaving many uncertain about water quality even now.