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Site Appraisal Defra NSTS (S1 hierarchy)

SuDS Feasibility Screener

Early-stage SuDS feasibility: site constraints, infiltration potential and component shortlist.

1

Site Parameters

2

Component Comparison

3

Treatment Train

Site Parameters

Define the characteristics of your site. These parameters will be used to assess feasibility for all SuDS component types.

Project Information

Project Name

Site Reference

Engineer Name

Date

Area & Land Use

Site Area (ha)

Impermeable Area (m²)

Land Use Type

Soil & Groundwater

Soil Infiltration Rate (mm/hr)

Custom Rate (mm/hr)

Groundwater Depth (m)

Rainfall & Climate

Design Rainfall (mm/hr)

Climate Change Allowance (%)

Space Constraints

Available Footprint (m²)

Maximum Depth (m)

Note: If any parameters are unknown, select "Unknown" and the tool will flag components requiring site investigation.

Component Feasibility Matrix

Automatic feasibility assessment based on your site parameters. Storage volumes and costs are estimated.

Component	Feasible?	Storage (m³)	Footprint (m²)	Est. Cost	Treatment Level	Notes

Feasibility Legend

✓ Feasible
Component is suitable for this site with standard design.

✗ Not Feasible
Constraints prevent use without significant mitigation.

⚠ Requires Investigation
Further site investigation or specialist design needed.

Recommended Treatment Trains

Based on site feasibility, three optimal treatment train combinations are shown below. Each offers different trade-offs between treatment performance, cost, and footprint.

Compliance Assessment

Run feasibility screen to predict S2 compliance.

Export Report

Generate a PDF summary of this feasibility assessment to share with your team or regulatory body.

Engineer's Notes Optional, included in PDF report

Regulatory framework (England)

This tool's outputs are designed to support compliance with the UK planning and flood-risk framework current as of 2026-05-15. Engineers and planners should verify the live version of each cited document before relying on this tool for a submission.

NPPF para 182 (National Planning Policy Framework, December 2024 edition; was para 167 in the 2021 edition): applications which could affect drainage on or around the site should incorporate sustainable drainage systems to control flow rates and reduce runoff volumes, proportionate to the nature and scale of the proposal. For major development, SuDS should take account of advice from the Lead Local Flood Authority, have appropriate minimum operational standards, and have maintenance arrangements in place to ensure operation over the lifetime of the development. The December 2024 update removed the previous “major development only” limitation, so SuDS are now expected across all development with drainage implications.
NPPG SuDS chapter: Planning Practice Guidance, "Flood Risk and Coastal Change → Sustainable drainage systems" section (paragraph reference IDs 003–080). Sets out the runoff destinations hierarchy, design principles, multifunctional benefits and adoption/maintenance expectations that operationalise the NPPF policy.
Schedule 3 of the Flood and Water Management Act 2010: originally anticipated for England in April 2024 following the Defra written ministerial statement of January 2023, but not yet formally commenced as of 2026-05. Defra published the 2025 National Standards for Sustainable Drainage on 30 July 2025 in preparation. Planning authorities, LLFAs and sewerage undertakers already treat the 2025 National Standards as the de-facto technical benchmark.
Non-Statutory Technical Standards (NSTS): Defra 2015, refreshed 19 June 2025; statements S1 through S7 covering runoff destinations, interception, peak flow, water quality, amenity, biodiversity and maintenance.
EA Climate Change Allowances: Environment Agency, May 2022 update (peak rainfall intensity, surface water). EA allowances are now provided per management catchment (UKCP Local projections); the national bands below (2050s central 20% / higher 25% / upper 35%; 2080s central 25% / higher 30% / upper 40%) are indicative only; confirm your catchment’s allowance from the EA peak-rainfall map.

This summary does not constitute legal advice. Where the regulatory position changes, the tool's outputs should be re-validated. Refer to the Quinnsite Methodology Registry, cited on every tool page and PDF report, for the pinned version-effective date of each cited methodology.