By KEVIN BEGOSPITTSBURGH (AP) â¿¿ What causes clear, fresh country well water to turn orange or black, or smell so bad that it's undrinkable? Residents of a western Pennsylvania community have been trying for more than a year to get that question answered in their quest to get clean water back. Some of them say the water was spoiled by drilling deep underground for natural gas. Others point to pollution from old coal mines. They've also been told it could even be a baffling mix of natural and manmade reasons that change the water over time, like the leaves change on trees. But no one knows for sure, and they say the uncertainty is maddening. In late 2011, the drinking water for about a dozen residents in the Woodlands, a rural community about 30 miles north of Pittsburgh, began to change. At first, the families blamed gas drilling, or fracking, being done 2000 feet away. But state tests showed the water wasn't contaminated by drilling, and even more confusingly, many of their neighbors reported no problems. Families with bad water then turned to federal officials. But last summer the U.S. Environmental Protection Agency quietly sent a letter to one resident, Janet McIntyre, saying the agency agreed with the state finding, since most of the chemicals found in the water could have occurred naturally. McIntyre wasn't satisfied, noting that the EPA "never set foot on my property to test the water themselves." The EPA didn't respond to a request for comment on why the agency didn't retest the water. Still, the residents with water problems were hopeful that the Atlanta-based U.S. Agency for Toxic Substances and Disease Registry was looking at the issue. But last month the agency said it "is not actively investigating complaints from this area." "I'm just very, very frustrated," McIntyre said.