WATER PLANT OPERATOR TRAINING PROGRAM


Use of Indicator Organisms in Water Treatment


  1. Indicate contaminated raw water
  2. Absence indicates effective treatment
  3. Indicate distribution system quality problems


  • Indicator organisms, e.g. fecal coliforms are excreted in large numbers in feces of healthy individuals – millions per stool.
  • Persons suffering from intestinal infections will excrete both normal flora and pathogens – pathogens will be fewer in number, therefore, less easy to detect in samples.
  • Generally, pathogenic bacteria are more susceptible to adverse conditions than indicator organism.
  • Coliforms and other indicators are more resistant to chlorine than bacteria which cause enteric disease.
  • If the treatment process eliminates all coliforms, and other drinking water parameters are met, e.g. turbidity and chlorine residual, we are reasonably assured that all disease-producing bacteria have also been destroyed.