Water supply wells shall be located at least _____ from the building sewer.

The correct answer is based on the established guidelines that dictate the required distance between water supply wells and building sewers to ensure the safety and integrity of the drinking water supply. Specifically, a distance of 15.20 meters is recommended to minimize the potential for contamination from sewer effluents, which may contain pathogens and other harmful substances that could infiltrate the well water.

The rationale for this distance includes the inability of certain contaminants to travel far and the degradation of many pathogens and nuisances in the environment over distance. By maintaining a buffer of 15.20 meters, the likelihood of contaminants reaching the water supply through groundwater movement is significantly reduced.

This specific distance is backed by regulatory guidelines and considerations of hydrogeology, which assess how water flows through soil and rock layers, ensuring a higher level of safety for individuals using well water. This is important for public health, as it helps to safeguard communities from waterborne diseases that could arise from exposure to contaminated water sources.