When is a strategy needed?
The NPPF published on 17 August 2026 identifies drainage information under policy F8 and Annex C for proposals that could affect drainage conditions onsite or nearby. The detail should be proportionate to the development and the drainage issues. Check the council's validation list as well as the national policy. [2] [3]
For an Epping Forest proposal, use the district's requirements and relevant Essex SuDS guidance. Do not assume a drainage submission prepared for a London borough can be reused unchanged outside London. [4] [5]
What does a useful strategy contain?
It should explain the existing drainage, the proposed catchments and discharge arrangements, the evidence supporting the design, and how the system will perform and be maintained. The national SuDS standards address water quantity, water quality, amenity, biodiversity and the practical management of the system. [1]
A useful commission asks the designer to show:
- Where runoff comes from and how it moves through the site.
- Which management and discharge options have been considered.
- What surveys, testing or approvals are still needed.
- How exceedance flows and future maintenance will be handled.
Ask for drawings that can be coordinated with the landscape and architectural plans, not only a calculation report with no visible space allocated for its proposed features.
Where should the water go?
The national standards establish an order of preference that starts with collection for non-potable use, followed by infiltration, discharge to a surface-water body, a surface-water sewer and finally a combined sewer. The designer should explain why a higher-priority option is not appropriate rather than select the easiest connection without evidence. [1]
Ground conditions, contamination, groundwater and available space can influence the solution. Where infiltration is proposed, ask what evidence supports it and whether the ground investigation and contamination assessment have identified any conflict. [1] [6]
Who prepares it?
A drainage or civil engineer should coordinate the hydraulic design with the architect, landscape designer and relevant ground specialists. Agree the required level of detail with the planning authority and, where relevant, the lead local flood authority. The national standards emphasise early, integrated consideration of the site's conditions and long-term management. [1]
Clarify whether the appointment includes a planning-stage strategy only or also detailed construction design, applications to other bodies and later verification. These are useful scope distinctions when comparing quotations.
Standards, policy and approvals are different
The national SuDS standards published in June 2025 are described by government as non-statutory. Their role in planning should not be confused with a separate permission to connect to a sewer or an assumption that every proposed system has been technically approved. [7]
Before construction, make sure the final layout still contains the drainage features and access needed for maintenance. Keep the agreed ownership and maintenance responsibilities with the completed project's records.