Gross pollutants traps are filtration systems that are designed to prevent stormwater pollution from entering the waterways. They are usually designed to catch the larger trash and debris as well as silt and larger sedimentation. The processes used in gross pollutants traps arent usually complex, utilising physical removal processes such as physical screening, rapid sedimentation and various separation processes such as hydrodynamic separation. They are usually designed to remove particles larger than 5mm.

There are several reasons why a gross pollutant trap is required and many more advantages. These primary treatment systems have a relatively small environmental footprint, usually being installed underground and have minimal impact on the environment. Once the primary treatment processes conclude, they are usually used in a treatment train with other stormwater treatment measures such as tertiary treatments or bio retention systems. Finally they remove the non-biodegradable, larger pollutants that would cause blockages, clogging or restrict water flow in further downstream systems and hence reduce the frequency of maintenance and increase the long life of the following treatment train systems.

Gross pollutant traps are commonly installed with secondary or tertiary treatment systems as a treatment train as they do not have the ability to remove fine sediment, dissolved pollutants, nutrients or other attached pollutants.

For more information and data sheets and installation instructions on a wide range of Gross pollutant trap sizes visit

Written by Nathan D. Raco, in partnership with Protector Stormwater management Solutions