Microorganisms that contaminate a water source are referred to as what?

Microorganisms that contaminate a water source are indeed often referred to as "microbes." This term encompasses a broad range of microscopic organisms, including bacteria, viruses, and protozoa, that can be present in water. The presence of these microbes is significant because they can lead to waterborne diseases and health risks for individuals consuming or coming into contact with the contaminated water.

While "contaminants" might seem like a relevant choice as it includes all sorts of impurities in water, it does not specifically refer to microorganisms. Similarly, "pathogens" refers specifically to disease-causing microorganisms and while it may apply to certain contaminants found in water, it does not encompass the whole range of microbes, some of which may not necessarily be harmful. "Toxins" refer to harmful substances produced by living organisms and are not synonymous with microorganisms themselves.

By referring specifically to "microbes", one accurately identifies the group of organisms that can compromise water quality and pose health risks, highlighting their role as potential agents of contamination.