Sustainable Buildings SPD
8. Sustainable Water Management
8.1 Surface water flooding is caused when local drainage capacity is unable to cope with peak rainfall events. Increased areas of hard standing created through new development prevents surface run off from draining away. The need to control this run off is important in order to reduce the risk of flooding.
Sustainable Drainage Systems (SUDS)
8.2 In accordance with policy DP11 the Council encourages the use of sustainable drainage systems for the disposal of surface water. SUDS can take various forms depending on the location, size and type of development.
8.3 Green roofs use vegetation and other organic matter to absorb rainwater and reduce run off from the building’s roof. This can also act as insulation and in some cases provide open space for the development.
8.4 Permeable paving such as pebbles, gravel or crushed stones can be used on hard surfaces such as car parks as these allow surface water to infiltrate into the ground. This does not however, negate the need to provide disabled access to comply with building regulations. In the future the Government may remove permitted development rights to pave over front gardens using impermeable paving.
8.5 Soakaways allow storm water to drain away from buildings and paved areas and permeate into adjacent soil.
8.6 Balancing ponds provide a temporary storage facility to reduce the risk of flooding. They are particularly useful in larger developments where there is likely to be an excess of surface water at certain times.
8.7 Swales and basins reduce and manage peak water flows, provide temporary storage for storm water, assist in filtering pollutants and aid the infiltration of water into the ground.
8.8 In all cases the applicant should indicate where applicable, who will be responsible for the maintenance of these systems.
8.9 Where SUDs are not used the applicant will be expected to fully justify why this is the case and that all options have been thoroughly explored. Failure to do this could result in the application being refused. Instances where SUDs may not be appropriate include:
- where there is no accessible outdoor space such as a garden or roof area,
- where it can be demonstrated that it would not be financially viable. For example in the case of small developments (such as extensions)
- where it can be demonstrated that there would be no increase in the volume of surface water (such as a change of use proposal)
Water Conservation Measures
8.10 Design measures can also help in reducing the demand for water by encouraging greater efficiency. The Council would encourage greywater recycling such as the reuse and recycling of domestic waste water and the use of rain harvesting systems. In residential developments water butts, dual flush toilets and energy efficient showers should all be considered as standard.