A modelling approach is presented to simulate infiltration systems in urban areas. The model consists of a hydrological sub-model and an infiltration system sub-model. Infiltration characteristics of individual facilities are first established using steady state numerical simulation of Richards' equation. These are represented as linear relations between the facility water head and infiltration rate for given facility widths. The infiltration system model is obtained by applying continuity equation to infiltration facilities lumped over a sub-catchment. This model is then coupled to a catchment runoff model to simulate storm runoff with infiltration systems. The model is applied to an infiltration system installation in a residential area, where stormwater runoff is monitored in a pilot area and a comparative area. The observed results suggest the method is adequate to evaluate the performance of infiltration systems. Except for the catchment storage routing parameter, all model parameters are determined from physical catchment characteristics.