Filterra® Bioretention

Filterra is similar to bioretention in its function and application, but has been optimized for high volume/flow treatment and high pollutant removal. Its small footprint allows it to be used on highly developed sites such as landscaped areas, parking lots and streetscapes. Filterra is exceedingly adaptable and can be used alone or in combination with other BMPs.


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Filterra – High Flow Rates, High Pollutant Removal

How Filterra Works

Stormwater runoff enters the Filterra system through a curb-inlet opening or pipe and flows through a specially designed filter media mixture contained in a landscaped concrete container. The filter media captures and immobilizes pollutants; those pollutants are then decomposed, volatilized and incorporated into the biomass of the Filterra system’s micro/macro fauna and flora. Stormwater runoff flows through the media and into an underdrain system at the bottom of the container, where the treated water is discharged.


Filterra Features and Benefits



High media flow rate (up to 140" per hour) Reduced footprint compared with traditional bioretention

Third party field testing confirmed that Filterra meets state regulatory requirements for pollutant removal under TAPE and TARP testing

Regulatory Compliance

Filterra offers the most cost effective stormwater treatment system featuring low cost, easy installation and simple maintenance


Landscaping enhances the appearance of your site making it more attractive while removing pollutants

Adds aesthetic appeal to your site

Available in multiple configurations and sizes

Flexibility to meet site-specific needs

No confined space access, and the first year of maintenance is included with the purchase of every system

Simple and easy maintenance


  • Inline
  • Offline
  • Peak Diversion
  • Bioscape Vault
  • Filterra Bioscape
  • Custom Configurations

Filterra Media – Proven Pollutant Removal

At the heart of all Filterra systems is Filterra engineered media; a specified gradation of washed aggregate and organic material homogeneously blended under strict quality controlled conditions. Using data from studies conducted by the University of Virginia, the filter media has been optimized to operate under high flow rates (up to 140 inches/hour) while maintaining pollutant removal performance. Filterra media is tested for hydraulic functionality, fertility, and particle size distribution to ensure uniform performance.

Pollutant Median Removal Efficiency Median Effluent Concentration (mg/L) Third Party Reference Studies
Total Suspended Solids 86% 3.3 UVA 2006, Herrera 2009, Herrera 2014, NC State 2015
Total Phosphorus (TAPE) 70% 0.05 Herrera 2014, NC State 2015
Total Nitrogen 34% 0.54 NC State 2015
Total Copper 55% 0.004 UVA 2006, Herrera 2009
Dissolved Copper 43% 0.003 Herrera 2009
Total Zinc 56% 0.04 UVA 2006, Herrera 2009, NC State 2015
Dissolved Zinc 54% 0.1 Herrera 2009
Total Petroleum Hydrocarbons 87% 0.71 Herrera 2009

Information above is based on results from third party field studies following industry recognized protocols such as TAPE and TARP. Relevant studies are noted for each pollutant, and corresponding data was aggregated to provide realistic and repeatable performance expectations.

Some jurisdictions recognize higer removal rates - see your Contech Stormwater Consultant for performance expectations.

Filterra Approvals

The Filterra has been verified by some of the most stringent stormwater technology evaluation organizations in North America, including:

  • Washington State Department of Ecology (GULD)
  • New Jersey Department of Environmental Protection
  • Maine Department of Environmental Protection
  • Maryland Department of the Environment (ESD)
  • North Carolina Department of Environmental Quality
  • Texas Commission on Environmental Quality
  • City of Portland, OR Bureau of Environmental Services
  • Virginia Department of Environmental Quality


  • Low Impact Development, Green Infrastructure, and Environmental Site Design
  • High pollutant removal requirements
  • New construction and urban retrofits
  • Pretreatment for above-ground or shallow below-ground storage
  • Shallow, decentralized treatment

Installation and Maintenance

We make it easy for you...

  • Vegetation selection guidance based on your climate zone.
  • On-site planting and activation included with every system.
  • The first year of maintenance is included with the purchase of every system.
  • Ongoing maintenance is simple.
  • - Clean biofiltration bay with simple landscape tools (rake and shovel).
  • No confined space entry required.
  • - Everything can be accessed from the surface.





To view documents simply click on (+) before the folder to view contents, then double click document file to open.
For Standard Details on vault sizes not listed below please contact your Contech Stormwater Design Engineer.


Regulatory Approvals

Based on more than 20 years of research and development, testing, and field monitoring, Filterra’s performance has been recognized by some of the nation’s most significant regulatory agencies. Filterra is the only manufactured treatment device:

  • Granted ESD (Environmental Site Design) status by the state of Maryland Dept. of Environment (MDE).  In fact, Filterra’s performance is recognized by MDE as superior to even their own public-domain micro-bioretention systems in their stormwater manual.
  • GULD-approved for ALL pollutants of concern with the state of Washington Dept. of Ecology (WA-Ecology). 
  • The most third-party-protocol tested, with (1) TARP, (2) TAPE, (1) NJCAT and (1) NCDENR tests completed

Filterra has achieved the following State approvals:

Virginia: Since 2002 (TARP)
Maryland:              Since 2002 (only MTD as ESD Practice)
Washington:            Since 2006 (TAPE – only MTD on ALL pollutants)
Massachusetts:         Since 2008 (TARP - MASTEP)
New York:              Since 2009
Maine:                 Since 2009 (TARP & TAPE)
TCEQ (Texas):          Since 2010
ODOT (Oregon):         Since 2010
OR DEQ UIC Program:    Since 2011
Pennsylvania:          Since 2012 (TARP)
Delaware:              Since 2013
Georgia (ARC):         Since 2013
New Jersey & D.C.: Since 2014 (NJCAT)

Filterra is offered in multiple configurations to meet site specific needs. These configurations make Filterra the most versatile decentralized stormwater BMP line on the market.

Filterra Standard Offline
The Filterra Standard Offline configuration is the most economical and simplest Filterra configuration. It utilizes a downstream catchbasin or curb inlet for bypass flows allowing for the shallowest profile and most flexible design of any of the Filterra configurations. It is ideal for both new and retrofit projects.

Filterra Internal Bypass – Curb
The Filterra Internal Bypass – Curb incorporates a curb inlet treatment chamber and internal high flow bypass in a single structure. This eliminates the need for a separate bypass structure and enables placement on grade or in a “sag” or “sump” condition.

Filterra Internal Bypass – Pipe
The Filterra Internal Bypass – Pipe treats piped in stormwater runoff from rooftops. Higher flows bypass the bioretention treatment via an overflow/bypass pipe design.

Filterra  – Street Tree 
The Filterra Street Tree contains openings in the concrete vessel for root expansion of trees with larger root balls.

Filterra – Sediment Chamber
The Filterra Sediment Chamber includes a sediment chamber that provides a settling area for large debris and sediments.

Filterra – Recessed Top
Filterra recessed tops allow a seamless integration using pavers, Mulch, or sod. Recessed tops increase the depth of the invert out.

Bucks County Justice Center (Phase 2)
Bucks County Justice Center (Phase 2)Doylestown, Pennsylvania
Prairie Line Trail
Prairie Line TrailTacoma, Washington
SouthfieldSouth Weymouth, Massachusetts
Capitol Highway
Capitol HighwayPortland, Oregon
Grande Dunes
Grande DunesMyrtle Beach, South Carolina
Pentagon Secure Bypass
Pentagon Secure BypassArlington, Virginia
Home Depot
Home DepotWilliamsburg, Virginia
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