Xylem technology focus: Building drought resilience through water reuse

Several UK water companies are actively planning indirect water reuse projects as part of their long-term drought resilience strategies. The projects reflect a transition towards new supplies that are independent from rainfall, helping address the five billion litres a day shortfall predicted by 2055 for water supplies in England. In this Q&A, Barry Hopton, Head of Client Relationships – UK Water Utilities, Xylem, highlights the proven technologies available to support these critical initiatives:

Large-scale indirect potable water reuse – or recycling – features in water companies’ 2025-2030 investment plans for the first time. What does indirect water reuse entail?

The practice of water recycling – treating and reusing wastewater - has been successfully implemented around the world for decades to help address water scarcity. By reusing water, communities can lessen their reliance on traditional freshwater sources and strengthen the resilience of their water systems to droughts.  

The process involves rigorously treating wastewater to meet water quality parameters for the intended use, whether potable or non-potable, which can be done in a variety of ways. 

Potable reuse is sub-categorised into direct potable reuse (DPR) and indirect potable reuse (IPR). DPR applies high-quality treatment to wastewater before directly blending it into the water treatment plant or distribution system. DPR plants are relatively rare but have operated successfully for decades.

Far more common globally, particularly in parts of North America, Asia, Australia and Europe - and soon the UK – is IPR. This process treats wastewater to the highest standards before discharging it into a water source such as a river or reservoir or injecting it back into the aquifer. It will ultimately be abstracted for drinking water supply. The river or groundwater acts as an environmental buffer between the treated wastewater and the downstream drinking water plant. 

While the exact reuse treatment requirements depend upon the waste stream, the process generally requires advanced treatments combined with disinfection or an advanced oxidation process (AOP). 

There are two main concepts of advanced water treatment for IPR.  RO-based advanced treatment is using reverse osmosis as major barrier, typically combined with pre-treatment by microfiltration or ultrafiltration and final polishing by UV-based advanced oxidation process (AOP). So-called carbon-based advanced treatment aims to avoid high costs and brine issues from RO and applies ozonation, biologically activated carbon (BAC) and granular activated carbon (GAC) filtration as main barriers, often followed by final UV disinfection.

Which countries in Europe have been most proactive in water reuse?

The major factor driving water reuse is water scarcity, therefore utilities in southern European countries like Spain are front-runners. The region of Murcia is reusing over 90% of its treated wastewater for agricultural irrigation. 

With the introduction of EU Regulation 2020/741, which sets minimum requirements for agricultural reuse, more countries are exploring water recycling. Even in Germany, generally considered a water-rich country, seasonal and regional water shortages have increased interest in water reuse. Potable reuse is less common in Europe, but there are a few successful IPR installations, e.g., in Barcelona, Spain, and Torreele, Belgium. 

What technologies has Xylem developed for indirect water reuse?

Advances in water treatment technologies, combined with economic and regulatory drivers, have made water recycling a cost-effective and sustainable way to safeguard supplies during droughts.

Xylem has several solutions for IPR, which have been successfully implemented around the world. UV-based advanced oxidation systems, which use hydrogen peroxide or free chlorine as oxidants, can serve as a final barrier after reverse osmosis (RO) - effectively targeting both chemical contaminants and pathogens.  In addition, our ozonation systems and the ozone-enhanced biofiltration solution, Oxelia, provides robust protection by removing pathogens and chemicals. 

Can you give an overview of Xylem’s experience with international water reuse projects?

Xylem has been involved in numerous water reuse projects globally, with a broad range of technologies. These include biological treatment, filtration, disinfection, ozonation and advanced oxidation processes. The technologies are demonstrating that wastewater can be purified well beyond drinking water standards and reused safely and economically for both potable and non-potable purposes.

For full-scale operational projects in Europe, we have installed equipment for agricultural reuse in several countries including Spain and France. Our pilot units are being used onsite in several German Federal Ministry of Education and Research (BMBF) funded research projects for non-potable reuse.

These pilots have not only proven our technical capabilities but have also played a critical role in engaging communities and regulators. This approach aligns closely with the UK’s RAPID scheme for accelerating development of large-scale, strategic water infrastructure, which is increasingly focused on demonstration projects to address trust and prove feasibility.

In the US, our technologies have underpinned several flagship projects:

• Silicon Valley Advanced Water Purification Center in California uses Xylem’s Wedeco® UV systems as a final disinfection step before supplying high-tech industries
• In Los Angeles, Xylem’s Wedeco® MiPRO photo AOP was installed at the Terminal Island facility to produce high-quality recycled water. This was the first full-scale UV-AOP installation using free chlorine as oxidant in the world.
•  San Diego’s North City Water Reclamation Center deployed Xylem’s Wedeco® ozonation system and MiPRO photo AOP for potable reuse. 

What are the biggest technical or operational challenges in delivering reuse projects?

From a technical standpoint, water reuse is not inherently challenging. While the practice is new for the UK, the processes are well established, with proven technologies that can achieve virtually any required water quality. The key is working with specialists to select the right technology for the specific context and ensuring the supply chain has the capability and capacity to support it at scale.

There are, however, challenges to consider when it comes to project delivery. Unlike other global leaders in reuse, the UK currently lacks a defined regulatory framework for indirect potable reuse (IPR). This creates a unique hurdle: how do we select and validate technologies without clear national standards to guide us? 

In March 2025, Ofwat, the Environment Agency and the Drinking Water Inspectorate – through the RAPID initiative - said they would be “putting in place the right regulation to enable the safe and efficient application of reuse projects over the coming years”. Once established, this will be a key project enabler. 

Delivery challenges may also stem from limited public understanding and acceptance of water reuse. To overcome this, it is crucial that water companies, suppliers and regulators work together to deliver clear, consistent communication and robust stakeholder engagement. By building trust and addressing concerns transparently, they can secure public support and ensure the successful implementation of these vital projects.