Sustainable Drainage Systems (SuDS), sometimes known as Sustainable Urban Drainage Systems (SUDS), are designed to reduce the potential impact of new and existing developments with respect to surface water drainage discharges.

The idea behind SuDS is to try replicate natural systems that use cost effective solutions, like the Hebden 40, with low environmental impact to drain away dirty and surface water run-off through collection, storage, and cleaning before allowing it to be released slowly back into the environment, such as into water courses. This is to counter the effects of conventional drainage systems that often allow for flooding, pollution of the environment - with the resultant harm to wildlife - and contamination of groundwater sources used to provide drinking water.

The paradigm of SuDS solutions should be that of a system that is easy to manage, requiring little or no energy input (except from environmental sources such as sunlight, etc.), resilient to use, and being environmentally as well as aesthetically attractive. Examples of this type of system are reed beds and other wetland habitats that collect, store, and filter dirty water along with providing a habitat for wildlife.

Originally the term SuDS described the UK approach to sustainable urban drainage systems. These developments may not necessarily be in "urban" areas, and thus the "urban" part of SuDS is now usually dropped to reduce confusion. Other countries have similar approaches in place using a different terminology such as Best Management Practice (BMP) and Low Impact Development in the United States.

SuDS use the following techniques:

• source control

• permeable paving, like the Hebden 40

• storm water detention

• storm water infiltration

• evapo-transpiration (e.g. from a Green roof)

Unlike traditional urban stormwater drainage systems, SuDS can also help to protect and enhance ground water quality.