The Filterra® Bioretention System is packaged Plug and Play stormwater filtration solution that harnesses the power of nature to capture and remove pollutants, treating stormwater runoff.

Above ground, the systems plant species add aesthetics and value to the urban landscape, and are chosen for their aesthetical, functional and biodiversity-enhancing properties.

 While underground processes are at work effectively removing key pollutants such as Total Suspended Solids, Phosphorus, Nitrogen, Metals, Oil and Grease.

Designed to treat over 90% of the total annual runoff, Filterra works within a very small footprint and is an innovative practice in Water Sensitive Urban Design.

Filterra is well suited for the urban and high-density environment providing a highly effective, natural treatment process packaged inside a flow-through container that can be easily installed at new or existing commercial, residential and public roadway projects.

Optimised for high volume flow treatment and high pollutant removal, the Filterra works as efficiently as a traditional rain garden but in a footprint a fraction of its size. 

The Filterra meets or exceeds regulatory guidelines for pollutant removal requirements and has been tested and approved throughout North America and New Zealand.


How does it work?

Filterra is a bioretention system in a concrete box.

Contaminated stormwater runoff enters the filter box through the curb inlet spreading over the 75 mm layer of mulch on the surface of the filter media. As the water passes through the mulch layer, most of the larger sediment particles and heavy metals are removed through sedimentation and chemical reactions with the organic material in the mulch.

Water passes through the soil media where the finer particles are removed, and other chemical reactions take place to immobilize and capture pollutants in the soil media. The cleansed water passes into an underdrain and flows to a pipe system or other appropriate discharge point.

Once the pollutants are in the soil, the bacteria begin to break down and metabolize the materials and the plants begin to uptake and metabolize the pollutants. Some pollutants such as heavy metals, which are chemically bound to organic particles in the mulch, are released over time as the organic matter decomposes to release the metals to the feeder roots of the plants and the cells of the bacteria in the soil where they remain and are recycled. 


To find out more about Filterra please contact us or 0800 STORMWATER360


Filterra® Features and Benefits


  • High biofiltration media flow rate (up to 140”/hr+)      
  • Greatly reduced footprint versus traditional bioretention and LID solutions
  • Filterra system is packaged, including all components necessary for system performance
  • Quality control for easy, fast and successful installation 
  • Quick and easy maintenance - no specialist equipment required. First year of maintenance included 
  • Low lifecycle costs
  • Variety of configurations and aesthetic options. Integrates easily into any site or landscape plan
  • Proven Performance – the only proprietary product available in New Zealand to have an Enhanced Removal certification for Dissolved Metals from the Washington Department of Ecology 
  • Filterra® filter media has been optimised to operate under high flow rates while maintaining high pollutant removal performance 


Filterra® Approvals

  •  Approved for TSS, Phosphorus, Enhanced Dissolved Metals, Nitrogen and Oil