For years, the data centre industry has focused on one main metric: Power Usage Effectiveness, or PUE. The industry has made strong progress. Cooling systems are more efficient and energy use is better managed.
Water Usage Effectiveness, or WUE, has existed alongside PUE for some time. But in most projects, it has sat in the background. It has been treated as a reporting figure rather than a design driver.
As AI infrastructure grows, that is changing. Water is becoming a real constraint.
The Shift in How We Think About Cooling
AI and cloud growth are pushing data centres to new limits. Higher densities and larger sites mean more heat and more cooling demand. Traditionally, cooling systems are designed with energy in mind. Water is often treated as a secondary factor.
That assumption is no longer valid.
Water availability, water quality, and discharge limits are now affecting what designs are possible. In some cases, the most energy-efficient system cannot be used because of water constraints. In other cases, reducing water use leads to higher energy costs.
This is not a small issue. It is becoming a key design challenge.
The Water and Energy Trade-Off
Cooling systems depend on both water and energy.
- Air-cooled systems use less water but often require more power.
- Water-cooled systems are more energy efficient but use more water.
- Hybrid systems offer flexibility but add complexity.
Water quality also matters. Scaling, fouling, and biofilm reduce heat transfer. This makes chillers work harder and use more energy. Better water quality can improve system efficiency.
Water and energy are closely linked. They cannot be managed separately.
The Real Problem
The main issue is not technology. It is how decisions are made.
Cooling systems are often chosen early in a project. These decisions are based on energy and climate assumptions. Water strategy is usually considered later.
By then, it is too late to make major changes. There is no common approach that brings together:
- Cooling system design
- Water availability and quality
- Energy use
- Operating cost
This leads to inefficiencies that last for the life of the facility.
A Better Approach
Cooling systems should be designed with both water and energy in mind from the start.
This means:
- Choosing the right cooling system based on real site conditions.
- Considering water limits and quality early in design.
- Adjusting operations based on weather and load.
- Managing water quality to improve system performance.
This is a shift from focusing on one metric to looking at the whole system.
Where Hydroleap Fits
At Hydroleap, this is the problem we focus on.
We started with water treatment. Today, our work extends into cooling water system design, water management, and operational strategy.
We help partners:
- Understand how water and energy interact in their systems.
- Identify inefficiencies in design and operation.
- Improve performance through better water management.
- Support both design decisions and day-to-day operations.
Our technologies, such as electrooxidation (EO), and electrodialysis reversal (EDR), support this approach. But the main value is how these solutions fit into the wider system.
Better water quality is not just about meeting standards. It improves overall system efficiency.
Retrofitting Existing Cooling Systems
Water strategy is not only relevant for new data centre design. Many existing facilities already operate with cooling towers, chillers, heat exchangers, and water treatment systems in place. In these cases, the opportunity is not necessarily to redesign the cooling system, but to improve how the existing system performs.
Hydroleap units can be integrated as a retrofit solution to support water quality management within existing cooling loops or side-stream treatment systems. By improving circulating water quality, operators can reduce scaling, fouling, suspended solids, and biofilm formation. This helps maintain heat transfer efficiency and reduces the need for frequent cleaning, chemical dosing, and excessive blowdown.
The result is a more stable cooling system with lower energy and water consumption and lower operational cost. In this context, better water quality becomes a practical lever for improving the performance of existing assets, without requiring major changes to the core cooling infrastructure.
From Vendor to Partner
This also changes how we work.
Instead of coming in after systems are built, we aim to be involved earlier. This allows us to support design decisions and improve long-term performance. We work with developers, EPCs, and operators to align water strategy with cooling system design.
This approach creates better outcomes over the full life of the facility.
Looking Ahead
AI infrastructure will continue to grow. This will increase pressure on both energy and water systems. The challenge is no longer just about reducing energy use.
It is about balancing:
- Energy
- Water
- Cost
- Reliability
Organisations that continue to treat these separately will face limits. Those that take a system-wide approach will find new opportunities.
At Hydroleap, we believe water is no longer a secondary factor. It is a core part of how data centres are designed and operated.