SuDS can use an array of techniques and components of drainage systems that when combined together form a management train.

As surface water flows through a site, specific components are selected to support the SuDS system and mitigate the flow velocity and pollutants within the water system. The management train may include the following stages:

• Source control methods to decrease the volume of water entering the drainage/river network by intercepting run-off water on roofs for subsequent re-use (e.g. for irrigation) or for storage and subsequent evapotranspiration (e.g. green roofs). Where space is limited these techniques can be valuable.

• Pre-treatment steps, such as vegetated swales or filter trenches, that remove pollutants from surface water prior to discharge to watercourses or aquifers. These can be used where there is more space and the ability to incorporate such systems. When these aren’t possible there are man-made systems that replicate the removal of pollutants but will likely require greater maintenance.
• Retention systems that delay the discharge of surface water to watercourses by providing storage within ponds, retention basins, or wetlands. These can be advantageous for major applications and become areas which can increase biodiversity and be an area of amenity for communities.
• Infiltration systems, such as infiltration trenches and soakaways, mimic natural recharge. This allows water to soak into the ground and is a preferred technique. These should be consider first on all applications where possible. There is a requirement to appoint an additional specialist to conduct the tests.