The CSS115 Filtration Unit is designed for the safe and convenient handling of concrete washwater by dealing with the harmful waste on site. The purpose constructed filtration bag is manufactured from a 300gsm, 900mm cube non-woven geotextile fabric inner layer with a bulk bag protective external. Sand, gravel and suspended concrete particles as fine as 80 microns are separated from the concrete slurry generated from the washout of concrete trucks and other equipment onsite and from saw cutting, core drilling, grinding and grooving concrete. Excess water passes through the filter bag and is captured in the holding tank below for testing and treatment. This unit can also be used as a dewatering station for filtering sediment laden water on sites that need to control the amount of sediment or pollution runoff.