Common Questions
SuDS require a lot of maintenance.
Properly designed SuDS should be low maintenance. Maintenance of SuDS features should typically be easier than that of traditional drainage as the functioning infrastructure is typically at-surface and therefore both inspection and maintenance activities are generally easier when compared with traditional buried drainage systems.
SuDS take up too much space
Some types of SuDS intervention allow for the integration of SuDS without significantly increasing the footprint of infrastructure, enabling more sustainable development practices.
To ensure an effective SuDS system can fit within a development, SuDS design must be considered from the outset. SuDS can therefore help inform the development layout instead of having to fit in around plots once a layout has been fixed. Not being able to accommodate SuDS into a development is not a sufficient reason not to incorporate them as they should be considered from the outset.
Higher density developments can incorporate lower land-take features such as green roofs, downpipe planters and swales. They can also maximise multifunctional space with SuDS in recreational spaces.
SuDS increase the risk of mosquito breeding
Well-designed SuDS don’t allow for stagnant water which minimises the risk of mosquito breeding.
SuDS can’t be installed on clay soils
Clay soils do not prevent use of SuDS, they only impact the choice and/or design of specific features. While infiltration may not be possible, features such as swales, ponds or lined SuDS features can be used to store water at a higher level and help with interception.
Groundwater contamination
Groundwater contamination does not prevent the use of SuDS, it only impacts the choice and/or design of features. If infiltration is not possible due to groundwater contamination risk, SuDS features lined with impermeable membranes can still be used, for example.
SuDS can’t be installed on flat sites
On flat sites, management of runoff as close to the surface and the source as possible is most effective. Conveyance mechanisms can include kerbs and swales. Pumping should be a last resort.
Shallow groundwater levels
Shallow groundwater does not prevent the use of SuDS, it only impacts the choice and/or design of features. Where groundwater is shallow, SuDS features at or close to the surface should be used, using impermeable membranes with consideration for uplift. The use of such lined SuDS can still provide interception of the first 5mm, runoff attenuation, runoff treatment and added biodiversity and amenity benefits.
SuDS can’t be installed on steep sites
On steep sites, SuDS should include check dams and storage and can be staggered on slopes. This reduces runoff velocity and increases attenuation and infiltration, creating a more effective SuDS system.
SuDS will create more litter
Soft landscape areas can have the effect of trapping litter because of the planting. However, this is true of planting generally and is not specific to SuDS. Studies have shown that spaces that look more attractive and cared for suffer less littering than unattractive, poorly maintained spaces.