What is the minimum residual pressure in a distribution system without public notification?

A minimum residual pressure of 20 psi in a distribution system is critical for ensuring adequate water supply and preventing issues such as backflow. This pressure level is significantly important for maintaining a functional and safe water distribution system. At this minimum, the water supply can effectively reach customers and support standard operational needs such as firefighting and everyday water usage.

Additionally, keeping the pressure at or above this level helps to prevent the infiltration of contaminants into the system. If the pressure were to fall below 20 psi, there could be an increased risk of contamination due to backflow, compromising water quality and safety. Therefore, maintaining a minimum of 20 psi is a fundamental requirement that protects public health, ensuring that adequate water pressure is delivered and that the integrity of the distribution system is preserved.