A system for controlling a moisture content below a surface area, where the system is installable in a recess above which the surface area will be located. The system comprises a substantially water impermeable first layer, a porous second layer and a water control basin which comprises means for controlling a moisture level of the porous second layer. The system enables liquid from the water control basin to be transported through the second layer by utilization of capillary forces, providing for an efficient sub-surface irrigation system which is easy to maintain. A method for providing such an irrigation system is also disclosed.