What is a "pathogen" in the context of water testing?

A pathogen, in the context of water testing, refers to a microorganism that can cause disease. This includes bacteria, viruses, and protozoa that are harmful to human health when present in drinking water or recreational water sources. Testing water for pathogens is essential to ensure it is safe for consumption and use, as these microorganisms can lead to waterborne illnesses.

In contrast, beneficial bacteria and harmless components play positive roles in maintaining water quality or ecosystem balance but do not pose health risks. Measurements of chemical contamination pertain to the evaluation of pollutants and toxins in water, which is a different aspect of water quality testing and not related to pathogens. Recognizing pathogens in water testing is crucial in public health, ensuring that water is free from agents that could cause diseases in the population.