Position statement on nutrient-neutral requirements for new development

This statement provides our current position with respect to working with developers to provide nutrient neutrality capacity at our water recycling centres.

Wessex Water’s water recycling centres (WRCs) accept additional flows and loads from housing developments as we have planned sufficient capacity for allocated development.

1. Our WRCs and the environmental permits that govern them are designed to reflect increases in population levels due to development over a 25-year design horizon. A legal case in the Court of Justice of the EU in 2018 (known as the 'Dutch Nitrogen Case'), however, means that measures to mitigate the impact of nutrients in water bodies can no longer be postponed into the future.
2. Prior to the legal precedent set by the Dutch Nitrogen Case, nutrient neutral development had already been incorporated into planning policy for developments impacting the Hampshire Avon (relating to phosphorus discharges) and Poole Harbour (nitrogen discharges).
3. Natural England is the government’s adviser for the natural environment and is the arbiter of what is permissible in respect of nutrient neutrality and the obligations arising from the Dutch Nitrogen Case. In particular Natural England determines what nutrient neutrality is, which nutrients this applies to (phosphorus and/or nitrogen), and how this should be calculated and demonstrated.
4. As part of the planning process developers are required to demonstrate to the Local Planning Authority and Natural England that their development satisfies the requirements for nutrient neutrality. Natural England have developed some tools and resources to assist with this, although we note that some councils (including Somerset Council) have support from Natural England for their own nutrient calculators to be used.
5. Wessex Water has no influence over these requirements through the planning process. We can only accept flows from new developments once planning permission has been granted and the Local Planning Authority and Natural England are satisfied that the relevant nutrient neutrality tests have been achieved.
6. Wessex Water’s nutrient reduction targets are set by the Environment Agency, with input from Natural England as appropriate. Historical discharge permit limits at our WRCs were based on legislation and guidance at the time. Our current Asset Management Plan period (AMP8, 2025-2030) includes upgrades to achieve further nutrient reduction targets, to comply with the latest regulatory requirements. Details of current nutrient improvements, timescales and permits is available under the ‘Developers’ tab on our Drainage and Wastewater Management Plan.
7. Our plans include upgrades to comply with the Levelling-up and Regeneration Act 2023, which amended the Water Industry Act 1991 to require additional nutrient removal to achieve the Technically Achievable Limit for either phosphorus (0.25mg/l) or nitrogen (10mg/l) at WRCs serving populations of greater than 2,000 within specified areas by 2030.
   
   The sensitive catchments – as designated on 25 January 2024 – within the Wessex Water region are:
   • Hampshire Avon Special Area of Conservation (SAC) - Phosphorus
   • Poole Harbour Special Protection Area (SPA) - Phosphorus and Nitrogen
   • Somerset Levels and Moors SPA - Phosphorus.
8. Promoters of development sites considering standalone private treatment arrangements, should be aware that they will require Local Planning Authority, Natural England and Environment Agency approval. We will only consider adopting private treatment assets (such as package treatment plants, PTPs) or upstream sewerage networks if they are designed and constructed to adoptable standards.
   
   In considering options for managing treated foul effluent arising from PTPs, developers are at liberty to seek a sewer connection to our sewerage network for further treatment at our WRCs. Understandably, unless adopted, liability for the continued maintenance and operation of the PTP and network upstream of the point of connection to the public sewer will remain with the developer/owner. There is also no discount for pre-treated domestic sewage, with charges likely established via a bulk sewerage agreement if the PTP serves multiple properties.
9. Wessex Water has received queries from developers seeking to contribute towards planned phosphorus removal schemes at our WRCs to bring schemes forward, or to fund new schemes at our WRCs where no new (or additional) phosphorus removal is planned. Under our current economic regulatory framework this is not something that we are able to pursue.
10. The Government have launched a new Nutrient Mitigation Scheme to be administered by Natural England, although this remains in development and to date has limited catchment coverage. Some councils have developed their own nutrient mitigation schemes and there are a range of existing nutrient offsetting schemes and catchment markets within our region offering temporary and longer-term mitigation solutions for developers.

Toby Willison
Director of Strategy
On behalf of Wessex Water
August 2025

This position statement is periodically reviewed and updated in light of any new or revised regulatory guidance.