Southern Water strongly supports Policy S5 and the inclusion of “multi-functional green infrastructure” wording throughout, as explained further below.
Further explanation and justification:
Southern Water supports all requirements which seek to ensure that surface water is appropriately managed, as close to source as possible. We need planning policy to consider carefully the measures called for in response to the climate crisis, and ensure sustainable development is central to the local planning framework for planning applications coming forward.
Southern Water is strongly supportive of sustainable urban drainage solutions (SuDS) as these will be essential to establishing community resilience to the impacts of climate change into the future. Whilst we appreciate there may be a need for some flexibility, Southern Water considers SuDS essential for all development. This is in line with paragraph 167(c) of the National Planning Policy Framework (NPPF) (2023) that requires:
167(c) using opportunities provided by new development and improvements in green and other infrastructure to reduce the causes and impacts of flooding, (making as much use as possible of natural flood management techniques as part of an integrated approach to flood risk management)
Southern Water is working across our region to remove surface water from our networks in key areas. Even as we deliver this work, development continues to increase surface water run-off. To be resilient to the evolving impacts of climate change we must plan to ensure that rainwater is separated from wastewater in the design and construction of our communities. For more information on our work, and the root causes of releases from storm overflows, please see –
https://www.southernwater.co.uk/our-region/clean-rivers-and-seas-task-force/pathfinders/
https://www.southernwater.co.uk/our-performance/storm-overflows/storm-overflow-task-force
During heavy rain, local sewer networks’ drainage capability can be exceeded by the amount of rainwater entering pipes and storage tanks connected via roads, roofs and paved areas. When these fill up, storm overflows release excess water through outfalls into rivers and the sea to prevent flooding of homes and businesses. Storm overflows are part of the network’s original design and are regulated by the Environment Agency. Over time, the expansion of urban settlements as well as ‘urban creep’ (home extensions, conservatories and paving over front gardens for parking) have incrementally added to the amount of rainwater entering sewers, resulting in increased releases from storm overflows. As stated in Water UK’s 21st Century Drainage Programme;
“The country’s built environment is constantly changing and “urban creep” – home extensions, conservatories and paving over front gardens for parking – can all add to the amount of water going into our sewers and drains. Green spaces that would absorb rainwater are covered over by concrete and tarmac that will not. In fact, studies show that “urban creep” results in a larger increase in predicted flooding than new housing, because it adds more rainwater to these systems’.
In terms of community resilience to the impacts of climate change into the future, better rainwater management through SuDS is the preferred approach. Retrofit of sustainable drainage solutions can be challenging but is also exemplary of good practice, and can be particularly necessary in areas of urban creep.