Transforming Wastewater Into Clean Water

New Desalination Technology Supported By the Trial Reservoirs Initiative Uses 80% Less Energy

For the last three and a half years, a new technology that transforms wastewater into clean water using 80% less energy than conventional methods has been brewing. Now, with the help of the Climate Change Trial Reservoir, it’s ready to be put to the test in a full-scale pilot.

Reverse Osmosis: The Energy-Intensive Industry Standard for Desalination

For communities and countries struggling to access clean water, reverse osmosis (RO) has long been the go-to technology for producing safe drinking water.

RO reliably delivers high-quality water, even from heavily contaminated sources – this is why it’s been the industry standard for the past 50 years. Yet despite its effectiveness, the technology comes with significant trade-offs. RO systems require extremely high pressures (up to 60 bar) to operate, which translates to increased electricity use, carbon emissions, and equipment costs. The result is a technology which can be expensive to install and maintain. Furthermore, while it plays a vital role in water systems, it also takes a toll on the environment: in addition to CO₂ emissions, RO produces brine waste that’s difficult to dispose of. While utilities contend with escalating costs and the pressure to meet net-zero goals, RO’s high energy use and brine management challenges highlight the trade-off between water purity and sustainability.

Forward Osmosis: the Desalination Tech Closing the Resource Loop

Enter Waterwhelm, a Scottish tech developer and creator of a new technology to help address some of RO’s biggest drawbacks. Waterwhelm’s forward osmosis (FO) technology transforms an untapped by-product (waste heat, an invisible waste of energy that operators have already paid to generate) into a driver for clean water production. 

By capturing the waste heat produced at wastewater treatment sites and combining it with a portion of treated water, the FO process can generate a reliable supply of high quality water. This approach recovers value from waste, aligning with circular economy principles. FO closes the loop by operating at much lower pressures than RO, typically lower than 5 bar. This is where FO      shines: by running at low pressures and harnessing waste heat. Compared to RO, it can deliver an 80% saving in electricity consumption while cutting capital costs by 35%. It also reduces CO₂ emissions by a staggering 79%.

Scaling Up Success: Tackling the UK’s Water Challenges Through Innovation

Waterwhelm’s journey is now scaling from proof-of-concept to real-world use, thanks to the support of the Trial Reservoirs Initiative. Following a successful 3.5 year trial which proved the FO concept, the technology is now ready to grow in partnership with Veolia and as part of the Climate Change Trial Reservoir. The new 18-month project will see the FO technology installed at Scottish Water’s Seafield Waste Water Treatment site, operated by Veolia. Here, the tech will need to prove its mettle as it scales up from producing 5 m³ of water per day to 55 m³/day. The goal is to demonstrate performance at a larger scale and to optimise the system, laying the groundwork for broader commercial deployment in future wastewater treatment projects.

This is a crucial step in tackling the UK’s water challenge. Ageing infrastructure, combined with rising energy costs and mounting environmental pressures, will force utilities to rethink how water is sourced and treated. The publication of the Cunliffe Report earlier this year reiterated this urgency, calling for ‘flexibility to enable innovative solutions that deliver the greatest environmental benefits’. This principle is at the core of Waterwhelm’s work, which reimagines how clean water can be produced more sustainably through the smarter use of existing resources. With nothing wasted, FO embodies circular economy principles, where every by-product becomes part of the next solution.

The Potential for Forward Osmosis to Drive a Circular Water Economy

Indeed, the Veolia site is already fully ‘off grid’, generating all of its own power and even supplying the grid with renewable electricity, reflecting Waterwhelm’s own circular economy values. While Veolia’s preferred technology approach is to utilise RO, the company continues to innovate in this space to improve the energy efficiency and carbon footprint of its use cases.

By applying these same principles beyond a single site, FO has the potential to make an even greater impact at wastewater treatment plants which are still reliant on fossil fuels. Based on preliminary estimates, the scaled-up trial system would reduce CO₂ emissions by approximately 382 tonnes each year – the same energy used to burn 175,000L of petrol, or power 70 average UK homes for a year. At the same time, the FO plant will produce enough clean water to meet the annual needs equivalent to a whole village or small town, all while cutting emissions and costs. 

This is no small feat. Though still at an early stage of development, if the technology works at scale it would demonstrate that wastewater treatment could become far less energy-intensive in the future. The ripple effects would extend far beyond individual wastewater treatment plants, with FO playing a pivotal role in decarbonising treatment infrastructure, strengthening water security, and accelerating the water environmental transition.

Scaling up Waterwhelm’s FO technology marks a significant technical milestone and a tangible example of how the water sector can align environmental responsibility with operational resilience. For utilities, it offers a pathway to decouple clean water production from high energy use and carbon emissions, supporting net-zero goals while cutting long-term costs. More broadly, it shows how innovation can turn resource-intensive processes into regenerative ones, lowering emissions, minimising waste, and protecting ecosystems that have long shouldered the burden of water treatment.

Trial Reservoirs Initiative: Powering the Possible

The Trial Reservoirs Initiative is helping technologies like Waterwhelm’s FO to gain the evidence needed to move from concept to commercial reality. With the Climate Change Trial Reservoir focused specifically on solutions that mitigate climate change, the Initiative helps to accelerate the adoption of proven technologies by providing loan funding, independent validation, robust KPIs, and shared accountability between tech developer and utilities. Together, these elements help remove the uncertainty that so often derails pilots before they can prove their value, bridging the gap between full-scale deployment and reducing the challenges that have held the sector back for so long. 

For utilities under growing pressure to deliver more for less, technologies like FO are set to demonstrate that sustainability and affordability don’t have to be opposing goals; rather, they can reinforce each other in a circular water economy. The Trial Reservoirs Initiative is proving that this future is within reach: by de-risking new technologies and promoting collaboration between innovators and utilities, it turns promising ideas into practical solutions, embodying a more resilient and sustainable water sector. 

The pilots supported by the Trial Reservoirs Initiative have achieved a remarkable 70% implementation success rate – nearly three times the industry average of just 25%. Discover how these technologies are reshaping the water sector in our case studies.