What is the pressure of distribution mains?

• A. 100 PSI high pressure
• B. 60 PSI medium pressure
• C. 5 PSI
• D. 0.3 PSI

Answer: (B)

Distribution mains are designed to maintain enough pressure to deliver adequate flow across the network while limiting stress on pipes and fittings. A typical operating pressure for distribution mains is about 60 psi. This level provides sufficient fire-flow and residential/service pressure over a wide area, while reducing the risk of leaks and damage that come with much higher pressures. Very high pressures, such as around 100 psi, are used only in special zones or with booster systems and are not the standard for the distribution network. Pressures as low as 5 psi or 0.3 psi would not reliably supply hydrants or normal service. So, about 60 psi represents the standard distribution mains pressure.