There are several classes of common water pol-lutants. These are  disease-causing agents (pathogens) which include bacteria, viruses, protozoa and parasitic worms that enter water from domestic sewage and untreated human and animal wastes. Human wastes contain concen-trated populations of coliform bacteria such as Escherichia coli and Streptococcus faecalis. These bacteria normally grow in the large … Read more