Guidance

The surface water investment model (SWIM) approach

Use this to help build a business case for investing in multiple small sustainable drainage systems (SuDS) features over a wide area.

• From: Environment Agency
• Published: 18 May 2026

Applies to England

Documents

The surface water investment model (SWIM) approach

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This guidance describes the surface water investment model (SWIM) approach. The SWIM approach aims to help the appraisal of multiple small SuDS features that deliver cumulative benefit. This will help to make the case for SuDS delivery and secure FCERM grant in aid (GiA) funding for surface water flood risk management.

Published 18 May 2026