The presence of a particular group of bacteria in water bodies indicates contamination. Identify the group.

Hint: There are a few categories of bacteria which act as indicator organisms for pollution. The presence of Coliform bacteria indicates contamination in water bodies. For example, Eschericia Coli.

Complete answer:
Thermotolerant coliform bacteria act like indicators for pollution in water bodies. There are various groups of bacteria that come under the coliform bacteria. They are generally found on the earth’s surface and can even be present on our skin. But they are harmless to human beings. They are also very easy to determine. The bacterias under coliform category do not cause disease, but the higher their number the greater chance of disease-causing bacteria to be present. If disease-causing bacteria is present, then gastrointestinal upset and general-flu symptoms can be seen.
The absence of coliform bacteria ensures that the water is microbiologically safe to drink. Therefore, the drinking water standard requires the complete absence of coliform bacteria. It also means that the drinking water should be free from Fecal coliform and Eschericia Coli. Some tests can also be done to free the water from Coliform bacteria. If the initial test indicates the presence of total coliform bacteria, extra tests for Eschericia Coli and fecal coliform must be done.

Note: Proper water testing requires that we get a sterilized sample from the laboratory and follow the instructions strictly. In order to avoid contamination in the long term, we should connect to the regional public water system, build a new, continuous disinfection system, use bottled water for drinking and cooking.