The municipal public water-supply company of Knokke-Heist is producing drinking-water from the dunes aquifer. However, the available resources are limited and overexploitation of the ecologically valuable dune aquifer system should be avoided. Therefore, the company has developed a new strategy for the future. An important component of this new strategy consists in the treatment of surface water by means of reverse osmosis, and remineralisation of the produced filtrate by means of groundwater taken from a new catchment around the “De Cloedt” pit, a former sand quarry, which is now inundated and recharged by surface water.