If coliform bacteria are present in the water supply, what might also be present?

The presence of coliform bacteria in a water supply is often indicative of fecal contamination, which may occur when sewage or animal waste enters the water system. Coliform bacteria serve as an important indicator organism because their presence typically suggests that harmful pathogens could also be present. These pathogens can include bacteria, viruses, and protozoa that can cause serious waterborne illnesses. Therefore, if coliform bacteria are found in the water, it is critical to suspect that pathogens could be present as well, posing a higher risk to human health. This connection underscores the importance of monitoring and testing for coliform as a way to assess overall water quality and safety.

In contrast, while harmless organic matter, heavy metals, and chlorine are important water quality factors, they do not have the same direct association with the presence of coliform bacteria. Harmless organic matter may exist independently in water without indicating contamination. Heavy metals typically originate from different sources, such as industrial runoff, and chlorine is often used as a treatment measure in water systems, but it doesn't correlate with indicating the potential for pathogens. Thus, the relationship between coliform bacteria and the likelihood of pathogens being present is what makes the selection of that answer particularly relevant.