There are three main stages to stormwater treatment and management. All three systems when combined from a complex but efficient treatment system that is able to remove almost all contaminants and pollutants, both physical or dissolved. the first stage is the primary treatment stage. This stage incorporates the removal of larger debris and trash and its usually seen as a gross pollutant trap. This stage is the vital part of the process as it is the first line of defense for the stormwater management system with the larger more damaging pollutants being remove as this point. These system mainly focus on the physical process of filtration such a physical screening, hydrodynamic separation and sedimentations. This primary process is designed to increase the longevity of the system, reducing maintenance frequency, reducing sediments load and maintaining steady flow of water.

The second stage in the treatment process is the secondary treatment stage. This stage is mainly focus on attempting to achieve the certain degree of effluent quality by using process to remove fine particles sedimentations, setting chambers and oil removal. These pollutants that are removed are all typically classified as non-attached pollutants such as sediments and oils. The most commonly used systems that are seen as secondary treatments systems is the oil separator and coalescing systems.

The final step in the stormwater management system is the tertiary treatment systems. These system are usually classified by enhanced sedimentation and filtration, biological update , adsorption and chemical filtration process. The pollutants that are usually aimed to be removed are nutrients, heavy metals and phosphorous, attached particles and bacteria. These system are usually more complex, using a range of media using a variety of chemicals processes to remove miniscule particles and attached pollutants. This secondary treatment process. After this final treatment process is completed and the desired pollutants levels are achieved the water is returned to the environment, to water  storage or retentions basins.