Southern Water has some requested changes to statements on pages 48 and 50 please (in addition to feedback on the policy that follows on below):
Paragraph 4.8.12:
Southern Water has developed the DWMP in consultation with Local Authorities, and fed outcomes into the AMP8 business plan proposals, for which the final determination is due from Ofwat in December 2024. We therefore suggest the following changes to this paragraph 4.8.12:
Southern Water is the primary provider for wastewater disposal within Medway and are currently developeding Drainage and Wastewater Management Plans in consultation with regional stakeholders across their catchments, including Medway. Drainage and Wastewater Management Plans are long-term plans that will provide an opportunity to improve water quality and drainage systems and will address pollution and flooding for the benefit of communities and the environment. These long-term plans take into account projected growth over the Local Plan period.
Paragraph 4.8.15:
We welcome the reference in paragraph 4.8.15 to Environment Agency guidance for the protection of groundwater quality, and ask if the Plan could also refer to the additional guidance that Southern Water has produced for sustainable urban drainage solutions within source protection zones here - https://www.southernwater.co.uk/media/ooubtggs/suds-in-spz-guidance.pdf
For effective and sustainable surface water management, we need to ensure the fullest range of SuDS options remain viable to developments, in appropriate locations, to:
• Secure the resilience of our communities into the future by enhancing surface water management in the most sustainable way whilst protecting the natural water cycle.
• Minimise future connections of surface water to foul/combined sewers.
• Ensure policy is enforceable whilst mitigating the risk of rogue behaviours by requiring appropriate levels of treatment in SuDS designs only where the conditions warrant it. Southern Water has produced ‘SuDS in SPZ guidance’ to support developers and policy makers when considering SuDS design.
Paragraph 4.8.18:
Currently paragraph 4.8.18 emphasises the need for SuDS in relation to sewer capacity, where the emphasis could be more effective when placed on the resilience of communities into the future in the face of climate change, as suggested in the changes we propose below:
SuDs measures are of particular importance also for new developments within areas where there may be sewer capacity limitations. Increased take up of SuDs will improve resilience of Medway over the Local Plan period and beyond and contribute towards climate adaptation.
Building Regulations H3 provides a drainage hierarchy whereby surface water should first discharge to a soakaway or other infiltration system where practicable, with discharge to the combined sewerage system a last resort. Development will not be allowed to drain surface water to the foul sewer, and Southern Water will resist new connections of surface water to the combined sewer, this is in line with our surface water management policy.

DM1 Flood & Water Management
Southern Water strongly supports the inclusion of sustainable urban drainage within this policy. However, we would also like to see this policy go further and make suggestions for additional policy wording below.
Requested additions:
Sustainable Urban Drainage:
• Existing surface water flow routes and drainage features within the site should be identified and preserved wherever these contribute to sustainable drainage eg ditches, seasonally dry watercourses, historic ponds.
• To minimise the risk of sewer flooding and protect water quality, surface water will not be permitted to discharge to the foul or combined sewer network.
• For infiltration SuDS within source protection zones, as part of their planning application Developers should provide evidence of having consulted the statutory water company responsible for the SPZ, to confirm the proposed SuDS design is appropriate to this sensitive hydrogeological location.

Further explanation and justification:
Southern Water supports all policy requirements which seek to protect public drinking water supplies and ensure that surface water is appropriately managed, as close to source as possible. We also need to ensure that design of developments will not mean that rainwater continues to run off homes and surfaces so fast that it causes flooding.
In terms of future flood risk, better rainwater management through SuDS is the preferred approach to avoid placing added pressure on drainage networks during heavy rainfall. We therefore strongly support the requirement to include SuDS within all development. This is also in line with the requirements of paragraph 167(c) of the 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)
Building Regulations H3 provides a drainage hierarchy whereby surface water should first discharge to a soakaway or other infiltration system where practicable, with discharge to the combined sewerage system a last resort. Development will not be allowed to drain surface water to the foul sewer, and Southern Water will resist new connections of surface water to the combined sewer this is in line with our surface water management policy here:
https://www.southernwater.co.uk/media/l23dbon0/surface-water-management-policy-120724.pdf
Measures should support the attenuation of flows of surface water run-off from rainfall, as well as surface water infiltration into the ground wherever possible in the local environment (see our policy on SuDS in source protection zones below).
Whilst some parts of the wastewater network were originally designed to accommodate surface water, the expansion of towns and cities, and ‘urban creep’, contributes to increases in surface water run-off. 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’.
As set out in Defra’s Storm Overflows Discharge Reduction Plan “Water companies must remove rainwater from the combined sewer system as part of effectually draining their areas. This should include limiting any new connections of surface water to the combined sewer network, and any new connections should be offset by disconnecting a greater volume of surface water elsewhere within the network". This aligns with Southern Water’s work to address problems caused by excess surface water in our sewerage network in order to protect water quality in rivers and sea. For more information please see –
https://www.southernwater.co.uk/our-performance/storm-overflows/storm-overflow-task-force and
https://www.southernwater.co.uk/media/7459/stormoverflows_faq.pdf
Even as we deliver this work, development continues to increase surface water run-off. For communities to be resilient to the evolving impacts of climate change into the future, we need planning policy to ensure that development does not increase flood risk elsewhere. Please also see our policy statement on Sustainable Development here:
https://www.southernwater.co.uk/media/ny0nb3qu/our-policy-statement-on-sustainable-development-a4.pdf
As both a water and wastewater company, Southern Water is a key stakeholder for sustainable drainage solutions (SuDS). SuDS include both infiltration and attenuation measures. Infiltration SuDS are not always appropriate within Source Protection Zones, further explanation is provided in our policy here - https://www.southernwater.co.uk/media/ooubtggs/suds-in-spz-guidance.pdf
The Environment Agency is the regulatory authority on protection of groundwater sources. Southern Water has developed additional guidance in consideration of potable water standards to help safeguard the water quality of SPZ through the responsible design of SuDS.
Whilst we appreciate that not all water companies might want to work in the same way, Southern Water needs planning policy wording to help ensure Developers consult Southern Water on their infiltration SuDS designs within SPZ. This will help to ensure infiltration SuDS designs remain as viable as possible per site, whilst being appropriate for their location.