“Many of the issues you are examining are several years old, and many have been addressed,” West Virginia officials wrote in a statement. The state’s pollution program “has had its share of issues,” regulators wrote. However, “it is important to note that if the close scrutiny given to our state had been given to others, it is likely that similar issues would have been found.”

More than 350 other companies and facilities in West Virginia have also violated the Clean Water Act in recent years, records show. Those infractions include releasing illegal concentrations of iron, manganese, aluminum and other chemicals into lakes and rivers.

As the water in Mrs. Hall-Massey’s community continued to worsen, residents began complaining of increased health problems. Gall bladder diseases, fertility problems, miscarriages and kidney and thyroid issues became common, according to interviews.

When Mrs. Hall-Massey’s family left on vacation, her sons’ rashes cleared up. When they returned, the rashes reappeared. Her dentist told her that chemicals appeared to be damaging her teeth and her son’s, she said. As the quality of her water worsened, Mrs. Hall-Massey’s once-healthy teeth needed many crowns. Her son brushed his teeth often, used a fluoride rinse twice a day and was not allowed to eat sweets. Even so, he continued getting cavities until the family stopped using tap water. By the time his younger brother’s teeth started coming in, the family was using bottled water to brush. He has not had dental problems.

Medical professionals in the area say residents show unusually high rates of health problems. A survey of more than 100 residents conducted by a nurse hired by Mrs. Hall-Massey’s lawyer indicated that as many as 30 percent of people in this area have had their gallbladders removed, and as many as half the residents have significant tooth enamel damage, chronic stomach problems and other illnesses. That research was confirmed through interviews with residents.

It is difficult to determine which companies, if any, are responsible for the contamination that made its way into tap water or to conclude which specific chemicals, if any, are responsible for particular health problems. Many coal companies say they did not pollute the area’s drinking water and chose injection sites that flowed away from nearby homes.

An independent study by a university researcher challenges some of those claims.

“I don’t know what else could be polluting these wells,” said Ben Stout, a biology professor at Wheeling Jesuit University who tested the water in this community and elsewhere in West Virginia. “The chemicals coming out of people’s taps are identical to the chemicals the coal companies are pumping into the ground.”