Sand filters, also called media filters or filtration basins, is a stormwater quality treatment system that works by capturing stormwater runoff and allowing this water to percolate through a sand-based filter media. Sand filters are very effective at removing sediment and pollutants attached to sediment. They do not provide reductions in the volume of runoff and have limited effectiveness for dissolved pollutants unless they are modified. They are suitable for all land uses, as long as the contributing drainage areas are limited (e.g., typically less than 5 acres). Media filters are not as aesthetically appealing, which makes them more appropriate for commercial or light industrial land uses or in locations that will not receive significant public exposure. Media filters are particularly well suited for sites with high percentages of impervious cover (e.g., greater than 50%). Media filters are typically designed with an underdrain, which makes them a good option for treating potential stormwater hotspots (PSHs). They can also be installed underground to prevent the consumption of valuable land space (often an important retrofit or redevelopment consideration).

Fact sheet for filtration