S1–S7 Standards
The seven Defra Non-Statutory Technical Standards that govern every SuDS scheme in England. Each standard now has its own page with worked examples and calculator links.
S1: Runoff Destinations
The hierarchy of preferred runoff destinations: surface waters first, soakaways next, sewers last.
Open standard → S2S2: Management of Everyday Rainfall (Interception)
Intercept the first 5 mm of rainfall at source so everyday events never reach the drainage network.
Open standard → S3S3: Management of Extreme Rainfall and Flooding
Manage rare-event runoff: attenuation, exceedance routing, climate-change allowances.
Open standard → S4S4: Water Quality
Treat surface-water runoff using the CIRIA Simple Index Approach before discharge.
Open standard → S5S5: Amenity
SuDS must deliver multi-functional amenity benefits: accessible, attractive public space.
Open standard → S6S6: Biodiversity
SuDS must contribute to biodiversity: habitat creation, planting strategy, BNG.
Open standard → S7S7: Design for Construction, Operation, Maintenance, Decommissioning and Structural Integrity
Buildability, long-term operation, maintenance access, and end-of-life decommissioning.
Open standard →Last reviewed: 2026-05-10 · Sources cross-checked against the canonical registry at the time of publication. Standards may be updated; verify currency against the publisher before relying on any citation.