An analytical solution of Laplace's equation is presented for appropriate boundary conditions associated with the problem of dual-pipe subirrigation and drainage. The solution describes stream function and hydraulic head within the groundwater flow region and likewise the associated water table shape. The solution is general and flexible. Response of the groundwater system can be studied relative to thickness of saturated zone, position of subirrigation and drainage pipes, heads in the subirrigation and drain'age pipes, crop evapotranspiration, fraction of inflowing subirrigation water that exits the drains, and the aquifer hydraulic conductivity. Calculations are presented showing how pipe spacing affects shape of water table. The general solution can be used also to predict salt flow through the system as well as water flow.