Parallelepiped-shaped monoblock for the treatment of first rain waters  realized in Polypropylene (PP), fully recyclable material, with extruded sheets, thermowelded with a continuous wire and carry suitably reinforced to withstand the pressures siltation and ensure walkability. consists of five compartments, primary oil removal / grit removal, floodway, water storage of 1 ^ rain, oil removal with lamellar pack, and the externally screening. The plant is equipped with rain sensor, electric lifting pump of 1st rain waters, automatic shut-off valve and the electrical protection and control with timer for a delayed start of 24/48 hours after the last meteor event. Access to compartments is guaranteed by inspection manholes and proper maintenance. All manufactured articles have inlet and outlet pipes suitably dimensioned, equipped with suitable  double lip gaskets.