What is a commonly accepted indicator of drinking water quality?

Coliform bacteria are widely accepted as a standard indicator of drinking water quality because they are generally present in the intestines of warm-blooded animals and can indicate the potential presence of pathogens in the water supply. Their presence signifies that water may be contaminated with fecal material, which can contain harmful microorganisms that pose health risks to humans. Coliforms are relatively easy and cost-effective to test for, making them a practical choice for water quality monitoring.

In contrast, while protozoan parasites, Cryptosporidium oocysts, and viruses are also significant concerns in terms of water safety, they do not serve as a general indicator of overall water quality in the same manner as coliform bacteria. Testing for protozoans and viruses typically requires more complex and expensive methods, and these pathogens may not always correlate with the presence of fecal contamination. Therefore, coliform bacteria remain the standard for indicating the microbiological safety of drinking water.