The primary origin of coliforms in water supplies is...

The primary origin of coliforms in water supplies is fosused on fecal contamination by warm-blooded animals. Coliforms are a group of bacteria commonly found in the intestines of warm-blooded animals, including humans. Their presence in water is often used as an indicator of contamination by fecal matter, which can introduce pathogenic organisms that pose a risk to human health.

When water sources are exposed to runoff from agricultural activities, improper sewage disposal, or wildlife, these bacteria can enter the water supply. Detecting coliforms is a critical step in assessing the microbiological quality of water and serves as an important public health measure to prevent waterborne illnesses.

Other options provided do not serve as primary sources for coliforms. For example, natural algae growth typically does not result in the introduction of these bacteria, nor do industrial solvents or acid rain present viable means for fecal contamination. Understanding these distinctions is vital for proper water quality management and protection of public health.