The New SuDS Hierarchy - Why Rainwater Harvesting is Now Priority number 1

The drainage industry is evolving, and the new National Standards for Sustainable Drainage Systems are showing us the way forward.

Published on 19 June 2025, these standards introduce a clear hierarchy for managing surface water runoff that puts rainwater harvesting at the top of the priority list. While these standards aren't mandatory yet, they demonstrate the clear direction our industry is heading - and smart developers are already embracing these changes. 

You can read the new standards here National Standards for Sustainable Drainage Systems

The New Runoff Destination Hierarchy:

1. Rainwater harvesting and reuse

2. Infiltration to ground

3. Discharge to surface water body

4. Discharge to surface water sewer

5. Discharge to combined sewer

This represents a fundamental shift from traditional approaches. Previously, we might have defaulted to soakaways or sewer connections. Now, we're being encouraged to think: "How can we capture and reuse this water first?"

Why This Matters for Your Project: 

Cost Savings: Reduced mains water consumption means lower utility bills

Planning Advantage: Demonstrating forward-thinking sustainability credentials 

Future-Proofing: Getting ahead of regulations that will inevitably tighten 

Environmental Impact: Reducing strain on water resources and sewerage systems

Practical Implementation: For a typical residential development, this might mean integrating underground storage tanks with pumping systems for garden irrigation, or above-ground water butts for smaller properties. Commercial developments could incorporate larger-scale systems for toilet flushing or cooling systems.

The Business Case: While initial costs may be higher, the long-term benefits are compelling. We're seeing clients who implement rainwater harvesting systems achieving 30-50% reductions in mains water consumption.

At The Drainage Designers, we're already helping clients navigate this new landscape. The question isn't whether these approaches will become standard - it's whether you'll be ahead of the curve or playing catch-up.