Fecal coliform bacterial testing may be determined by using either the multiple tube or the membrane filter procedure. The membrane filter technique has been shown to have 93 percent accuracy for differentiating between coliforms from warm-blooded animals and coliforms from other sources. Fecal streptococcal group organisms can also be identified by using either membrane filter or multiple tube methods. The normal habitat of fecal streptococci is the intestines of man and animals, making these organisms one indicator of fecal pollution. Further discussion on the microbiology of drinking water and testing methods can be found in Drinking Water and Health and Standard Methods for the Examination of Water and Wastewater.
Radioactive elements can appear in water supplies as a result of naturally occurring contamination.
Radioactive elements can also enter water from indiscriminate disposal of hospital or industrial radionuclides as well as a result of leakage from reactors. Radiological water quality standards are based on the premise that radiation has an adverse physiological effect on humans and any unnecessary exposure must be avoided. The physiological effects that are associated with overexposure to radiation demands the rejection of any treated water containing excess quantities of radionuclides. Proper treatment methods will provide drinking water of desired radiological quality in most cases. The University of Iowa.