Passive treatment systems use natural processes to remove and break down pollutants from surface water runoff.  Small scale systems such as filter strips, can be easily designed into the landscape and are sited upstream of other SUDS.  Larger, ‘end of pipe’ systems usually involve storage of water in constructed ponds.  Here natural purification processes can be encouraged.  Constructed wetlands and ponds also provide the opportunity to improve wildlife habitat in urban areas.  Additionally, ponds can be made into amenity features for the local community and there is growing evidence of the additional value this can provide to communities.

View sites in Wales with a Passive treatment system.