System Pressure Requirements
Domestic water supply systems must maintain a minimum residual pressure at each outlet. IPC §604.1 requires a minimum flow pressure of 8 psi for most fixtures and a minimum static pressure of 15 psi for any fixture. Flush valve water closets require a minimum of 25 psi flowing; flushometer urinals require 15 psi. Typical service pressures at the point of entry range from 40 to 80 psi; where the street pressure exceeds 80 psi, a pressure reducing valve (PRV) is required by IPC §604.8.