PURIFICATION AND SANITARY CONTROL OF WATER (POTABLE AND WASTE)

Although most of the streams draining inhabited regions are contaminated with human or animal feces, water-borne disease today in the United States is relatively uncommon. Pathogenic enteric microorganisms probably do not multiply in raw water sources under normal conditions. They usually disappear in a relatively short time, with the rates depending on variations in environmental conditions. Urban water supplies have played a diminishing role in the transmission of intestinal disease because of improvements in the detection and enumeration of pollution indicators, water and sewage treatment processes, and t h e sanitary control of water systems