The public health risks posed by water polluted by livestock manure are essentially the same as those posed by human sewage. Many of the same chemicals and biological organisms that pose health risks from exposure to untreated human sewage also pose risks to human health from exposure to raw untreated hog sewage.
Raw untreated hog sewage generates over 150 gases, many of which are harmful, including ammonia and hydrogen sulfide, plus another 150 toxins. The animal waste from 2,500 hogs in a confinement feeding operation, the minimum size to be classified as a CAFO, is equivalent to the human waste from a municipality of 8,000 to 10,000 people.
There are logical reasons for requiring sophisticated, multi-stage waste treatment systems whenever 8,000 to 10,000 people choose to residence in close proximity and form a municipality. These same reasons raise legitimate public concerns when the feces and urine from 2,500 hogs is being stored and spread untreated on farmland. The chemical and biological wastes can seep into groundwater to pollute the wells of rural residents and can run off fields into streams that provide drinking water for municipalities on their way to oceans. A class I CAFO of 17,500 hogs produces as much raw sewage as a city of 55,000 to 70,000 people.