Escherichia coli is the most common indicator of water pollution. It naturally occurs in the intestines of human beings and animals. They are commonly found in sewage and if E.coli are detected in water then it indicates fecal contamination. So if E.coli are detected in drinking water it indicates a serious health risk and that water should not be used for drinking. Hence, the correct answer is option 'B'.

Indicator Organism: Escherichia coli

Escherichia coli, commonly known as E. coli, is a type of bacteria that is widely used as an indicator organism in water pollution studies. It belongs to the family Enterobacteriaceae and is a normal inhabitant of the intestinal tract of warm-blooded animals, including humans.

Indicator of Faecal Matter Pollution

The presence of E. coli in water bodies indicates the contamination of water with faecal matter. Since E. coli is commonly found in the intestines of warm-blooded animals, its presence in water signifies the potential presence of pathogens that are associated with faecal contamination. These pathogens can include various disease-causing bacteria, viruses, and parasites.

When water sources become contaminated with faecal matter, whether through sewage leaks, improper waste disposal, or agricultural runoff, there is an increased risk of waterborne diseases. These diseases, such as cholera, typhoid fever, and gastroenteritis, can cause severe illness and even death.

Advantages of Using E. coli as an Indicator Organism

- Abundance: E. coli is abundantly present in the intestines of warm-blooded animals, making it a reliable indicator of faecal contamination.

- Easy Detection: E. coli can be easily detected and quantified using various laboratory methods. The most commonly used method is the membrane filtration technique, where water samples are filtered through a membrane that selectively retains E. coli. The retained bacteria can then be cultured and counted.

- Rapid Results: The detection and enumeration of E. coli can be performed relatively quickly, providing rapid results for water quality assessments.

- Specificity: E. coli is specific to faecal contamination and is not naturally present in non-polluted environments. Therefore, its presence in water is a strong indication of recent or ongoing contamination.

Conclusion

Escherichia coli is an important indicator organism used to determine the pollution of water with faecal matter. Its presence in water signifies the potential presence of pathogens associated with faecal contamination, highlighting the need for proper water treatment and sanitation practices to ensure the safety of drinking water sources.