Building materials, not of metal; plastics pipes, sheets, tiles, rolls, membranes and mats for storage, drainage, infiltration, seepage, leach structures and systems; plastic materials in this class for drainage purposes; non-metallic drainage systems; non-metallic conduits for drainage and irrigation; secondary drainage system consisting of non-metallic troughs and collection boxes; non-metallic silt barriers; reinforcement grids for use in soil stabilisation and water drainage; non-metallic drainage cells; geo-composites and geotextiles for the purpose of drainage, stabilising inclines, recultivation, plant support, absorption, filtration, separation, stabilization and reinforcement, including those having an integrated drainage network; geo-composites and geotextile sheeting, tiling and matting including such goods having an integrated drainage network; plastics underground storage, drainage, infiltration, seepage or leach structures and systems for the retention and dispersal of waste water and rainwater, including water permeable or perforated plastic underground storage, drainage, infiltration, seepage or leach structures and systems for the retention and dispersal of waste water and rainwater; plastics modular units to form said plastic underground drainage, infiltration, seepage or leach structures and systems.