Research on rainwater harvesting mainly focuses on a building scale. Scant information is available about its performance at large scale. This study aims to determine the potential for, and economic viability of meeting non-potable water demand by rainwater harvesting for a large scale case (21.5 km2): Amsterdam Airport Schiphol. A dynamic model was developed to analyse scenarios of varying rainfall, catchment surfaces and storage capacity. Four potential system configurations of catchments and non-potable uses were analysed for their economic performance with different water prices and storage options. This study found that, given sufficient storage and catchment size, all non-potable water demand of Schiphol can be supplied, reducing drinking water demand by up to 58%. Diminishing returns for adding storage and catchment to the system make full supply inefficient. Current water charges make most large scale system configurations not viable due to high investment costs for supply networks and storage infrastructure.