Which group of microorganisms serves as indicators of fecal contamination in water?

Bacteria serve as indicators of fecal contamination in water primarily due to their prevalence in the intestines of warm-blooded animals, including humans. The presence of certain types of bacteria, specifically fecal coliforms and E. coli, is an established practice in water quality assessment. These bacteria are not typically found in clean water sources, making their detection a reliable sign of fecal pollution.

Using bacteria as indicators is advantageous because they are relatively easy and cost-effective to detect in laboratory settings. The presence of these microorganisms indicates that pathogens that may pose health risks could also be present in the water, even if those pathogens are not directly tested.

Conversely, while viruses, protozoa, and fungi can also indicate water quality issues, they are not the standard indicator organisms for fecal contamination. Viruses may be present in fecal matter but are more difficult to detect and do not grow in laboratory conditions like bacteria do. Protozoa, such as Giardia, also signal waterborne pathogens, but they do not serve as the primary indicators due to their sporadic presence. Fungi are generally not associated with fecal contamination and are instead more commonly found in soil and decaying organic matter. Therefore, bacteria are considered the most reliable