The article vastly overstates it's conclusions to dangerous effects. A cursory search of medical literature finds plentiful epidemiological evidence. Cases of water borne sickness are not infrequently reported all over the country. One cannot rely on visual clues alone to confirm absence of human or agricultural activity nearby. Worse yet, backcountry hikers may quickly find themselves in a life-threatening situation even after a mild injury or persistent symptom, like diarrhea. A twisted ankle is no big deal in the city, but a serious medical emergency when you are on top of a mountain.
One does not have to buy the hype of big filter---just boil your water or use iodine to stay safe.
One does not have to buy the hype of big filter---just boil your water or use iodine to stay safe.