Fecal Coliform

Introduction

The concentration of fecal coliform bacteria in water is measured to determine the likelihood of contamination by microbiological organisms. While fecal coliform are not pathogenic (disease causing), they are commonly found alongside pathogenic organisms such as those responsible for dysentery, gastroenteritis, and hepatitis A. It is easier to test for fecal coliform than for pathogenic organisms; therefore, the presence of fecal coliform in a water sample is used to indicate potential contamination. A common source of coliforms and pathogenic bacteria is raw sewage. Fecal coliform bacteria occur naturally in the digestive tract of warm-blooded animals, where they aid in the digestion of food.

The results of coliform bacteria tests are generally used to monitor recreational areas, stormwater out-falls, and drinking water supplies. Water is commonly tested for three types of coliform bacteria: fecal coliforms, total coliforms, and E. coli. The standards for drinking water are generally based on total coliforms. The accepted standard for drinking water is that there should be no coliforms present after the water is filtered or treated. Natural waters will nearly always contain some form of bacteria. That is why you should never drink untreated water from a river or lake. Currently, the most common measurement for surface waters is fecal coliform. In some areas, standards for surface water contamination are shifting to the measurement of E. coli.

Objectives

• Determine the quantity of fecal coliform bacteria present in a water sample from a stream or lake.