IV-359 



problem of finding pathogenic organisms in water is difficult. The 

 methods available for determining the numbers of these micro- 

 organisms in sewage and receiving water are not practical for 

 routine use; nor is it possible to decide which organisms should be 

 included in the testing procedures. 



Evaluation of the microorganism density in water receiving waste 

 discharges is based on the test for the total number of viable 

 coliform bacteria present. This test procedure may be further extended 

 to differentiate between the total numbers and those of probable 

 fecal origin. The coliform bacteria in this instance are used 

 strictly as indicator organisms. Although the coliform organism has 

 been associated with infant diarrhea, it is generally considered as 

 non-pathogenic in water. The organism is present in fecal material 

 in large numbers, is highly viable in water, and 1s relatively easy 

 to identify. The use of an indicator organism is justified on the 

 premise that if col i forms of fecal origin are present, other 

 pathogens of fecal origin probably are present also. 



Although most human enteric pathogens do not survive for extended 

 periods outside the host's body, evidence indicates that they may 

 remain sufficiently viable in all types of aquatic environment to 

 reinfect healthy individuals. Although considerable Investigative 

 work has been done on fresh water and on oceanic water, many questions 

 are yet to be answered where the two meet in the estuarine zone. 



