There is a growing shortage of groundwater but still flooding, this because water cannot seep into the subsoil because of increasing paving (concrete, tiles, clinkers, etc.). Therefore, Flanders has had tightened legislation on rainwater since 1 January 2014; one must either collect rainwater/rainwater in a cistern or allow it to seep into the ground. Grass grids and gravel grids provide a water-permeable surface, therefore allowing water to easily permeate into the ground. This will both prevent groundwater shortages and also flooding without investing in an expensive drainage system. This reduces our ecological footprint and prevents the limitation of natural habitats.