WELL Accredited Professional (AP) Practice Exam

Coliforms are used as indicators of fecal contamination in water. Their presence signals that the water may have been exposed to sources from the intestinal tract, which raises the likelihood that other disease-causing pathogens—bacteria, viruses, and protozoa—could be present as well. Detecting coliforms prompts further testing and treatment because it doesn’t prove that water is unsafe by itself, but it warns that contamination may exist. Conversely, their absence doesn’t guarantee safety, and coliforms don’t indicate high mineral content or automatically confirm the water is safe to drink.