What type of bacteria is commonly tested for as an indicator of fecal contamination in drinking water?

The choice of Escherichia coli as a common indicator of fecal contamination in drinking water is based on its specific characteristics and its association with waste products. E. coli is a type of coliform bacteria that resides primarily in the intestines of warm-blooded animals, including humans. Its presence in water indicates that fecal material may be present, which can potentially contain harmful pathogens.

Testing for E. coli is a standard practice because it is easy to detect, and its abundance typically correlates with the presence of other, more harmful pathogens that might be in contaminated water sources. Furthermore, E. coli survives longer in water than many of the pathogens that are associated with fecal contamination, making it a reliable indicator of recent contamination and a red flag for the safety of drinking water.

In contrast, the other bacteria listed do not serve as efficient indicators for fecal contamination. For instance, Staphylococcus aureus is not specifically linked to gastrointestinal contamination; Salmonella, while a pathogen of concern, is not as ubiquitous in fecal matter as E. coli; and Mycobacterium species are unrelated to fecal contamination and would not imply the same public health concerns regarding water safety.