The Xtreamfilter is a highly efficient and comprehensive tertiary treatment filter that effectively removes TSS, phosphorus, nitrogen, gross pollutants, hydrocarbons, oils, and heavy metals. The filter is constructed with an outer FRP shell that surrounds a cylindrical cylinder filled with specially designed filtration media that targets specific contaminants using a range of filtration techniques. The water flows up the outer channel, horizontally through the dual filter media, and rises up the inner tube into the retention chamber before flowing out the outlet dropper pipe. The filter media is protected by a 1000-micron bag mesh and utilizes adsorption, precipitation, chemical filtration, physical filtration, and attachment techniques for removal. The outlet system can vary depending on the installation, with OSD in-situ concrete systems allowing for pipework concreted into the tank, or elevated PVC pipes, elbows, and tee systems. The system utilizes siphon filtration and self-cleaning techniques through backwash to ensure constant water flow and increase the lifespan of the filter media. Installation and maintenance are simple, and the system comes pre-assembled in a FRP horizontal encasing. The Xtreamfilter is an exceptional filtration system suitable for various site demands.