Waterloc is a cost effective and flexible way of providing underground stormwater storage for infiltration and attenuation systems or for rainwater harvesting purposes. The innovative design of Waterloc utilises columns of extruded polypropylene honeycomb structure, already widely used in stormwater storage applications, in a unique combination with injection moulded grids to provide both vertical and horizontal water flow. Waterloc is strong and lightweight and suitable for pedestrian and trafficked areas. Each cell has a volume of 250 litres with 96% voids. They can easily be used in a modular format to form a stormwater storage unit configured to suit the capacity required, soil conditions and the land area available.