Distribution system pressure should not drop below what value in psi?

In a drinking water distribution system, maintaining adequate pressure is crucial for both the safety and reliability of the water supply. The correct threshold is that distribution system pressure should not drop below 20 psi. This pressure level ensures that there is sufficient force to deliver water effectively to consumers and maintain the functionality of fire hydrants, which are essential for fire protection services. Additionally, pressure below this value can lead to issues such as backflow, where contaminants could potentially enter the drinking water supply due to negative pressure zones.

Setting the minimum at 20 psi also helps in preventing stagnation in the system, which can occur at lower pressures, thereby reducing the risk of water quality deterioration. Hence, maintaining distribution system pressure at or above this level is vital for both operational efficiency and public health safety.