In January 2025, the UK Water Reuse Association (UKWRA) launched Water Reuse Ready – a clear call to government that rainwater harvesting and greywater recycling systems are no longer optional but essential to securing the UK’s future water supply. Alongside this call came a practical roadmap for implementation, showing how reuse can be delivered safely and at scale across the country.
For forward thinking design engineers, this is the moment to act. The buildings you design today will be in use long after new regulations take effect, meaning the choices you make now will define their long term resilience to water scarcity.
This blog highlights the key insights and timelines from Water Reuse Ready, helping you anticipate incoming changes and integrate rainwater harvesting and greywater recycling into your specifications before they become mandatory.
The Need for Rainwater Harvesting and Greywater Recycling in the UK
The urgency for action is clear…
• 1.5 million new homes are planned over the next five years, adding further pressure to potable water infrastructure.
• Retrofitting reuse systems is on average 50% more expensive than including them at the design stage.
• Demand for commercial properties continues to grow, yet water companies are not legally obliged to provide new connections, limiting economic growth.
• Water neutrality requirements in parts of England are already restricting new development.
• Much of England is now officially classed as “seriously water stressed” by the Environment Agency.
Water Saving Potential of Water Reuse
Commercial Sector
Around 2,600 new commercial properties are built in the UK each year. Independent research by Ricardo found that large scale buildings with water reuse systems can save an average of 10m³ of water per day.
If every new commercial property built between 2026 and 2050 incorporated rainwater harvesting or greywater recycling, this would deliver a daily saving of 650 megalitres across 65,000 properties.
Domestic Sector
The potential in housing is even greater. If the UK builds 250,000 new homes per year between 2026 and 2050, and each property includes a water reuse system, this would save 375 megalitres of water per day.
National Impact
Combined, these measures could save 1,025 megalitres daily covering 20.5% of the UK’s projected national water deficit. This demonstrates that widespread adoption of rainwater harvesting and greywater recycling systems is not just desirable but critical.
Current UK Regulatory Environment
The UK’s regulatory framework still presents barriers to water reuse…
• The Water Industry Act 1991: This legislation states that water companies can only provide “wholesome” water for “domestic purposes” which includes toilet flushing. This prevents water companies from delivering communal rainwater harvesting or greywater recycling schemes.
• Building Regulations Part G 2010: While the regulations recognise alternative water sources as a way of improving efficiency, their inclusion is not mandatory. As a result, many new developments bypass reuse altogether.
The Roadmap to Mandatory Water Reuse
The UKWRA proposes a phased approach to regulation…
• 2025 Establishment of a government advisory group on water reuse.
• 2026 Updates to the WaterSafe accreditation to include rainwater harvesting and greywater recycling system installation and maintenance.
• 2027 Introduction of aligned legislation to support large scale adoption.
• 2028 Mandatory water reuse in all water stressed regions of England.
• 2030 Mandatory water reuse in all new buildings across the UK.
Key Takeaways for Engineers and Developers
• Keep your knowledge of rainwater harvesting systems and greywater recycling systems up to date through CPD training.
• Begin specifying water reuse systems wherever possible to future proof buildings and mitigate the UK’s growing water scarcity.
• Housing developers should start engaging with communal water reuse models now to stay ahead of regulatory change.
Final Thoughts
Water reuse is no longer a “nice to have” it is essential for the UK’s resilience against climate change, population growth, and water scarcity. The upcoming regulations will make rainwater harvesting and greywater recycling a standard requirement. Acting early gives engineers, architects, and developers a competitive edge while contributing to the UK’s long term water security.
