Abstract: A computer-implemented system for designing a pressure-dosed drain field comprising: a screen that allows a user to specify length and diameter for pipes that comprise the forcemain and discharge assembly, specify the pumping liquid level and discharge elevation, select the number of laterals and enter a specified residual pressure, enter or select a coefficient to be used in calculating friction losses, and enter the diameter and length of each manifold segment; a minor loss screen that calculates minor losses based on fitting selections made by the user; a pump file; a tabulated results screen; a gauge screen; and system and pump curves. A computer-implemented method of using the above system to design a pressure-dosed drain field. The purpose of the system and method is to enable an engineer to design a pressure-dosed drain field that will meet regulatory requirements for the system flow differential.