How it works

The system consists of a concrete container, a 75mm mulch layer, 500mm to 1000mm of a unique soil filter media, an observation / cleanout pipe, an under-drain system and an appropriate type of plant i.e., flowers, grasses, shrub, or tree.

Stormwater runoff drains directly from impervious surfaces through an inlet structure in the concrete box and flows through the mulch, plant, and soil filter media. High pollutant removal efficiency is achieved due to the multiple natural tratment systems inherent in this unique media blend through a variety of physical, chemical and bioligical procsses. Treated water flows out of the system via an under-drain connected to a surface water drain, soakaway / infiltration system or other appropriate outfall.

Filterra™ can also be used to control runoff volumes / flows by adding storage volume beneath the filter box for either infiltration or detention control (e.g. a Stormbloc® or Stormcell® system beneath the box).

The concrete container and treatment media are below the surface of the adjacent hard surfaces with the only features visible being the top concrete slab, tree grate, plant, and inlet opening. Filterra™ looks very similar to an ordinary tree box except that it is specially designed to treat runoff. This is one of the few commercially available SUDS systems that can also help to enhance the aesthetic value of the urban setting.