Water consumption by data centers: A wrong issue?

Data centers are often portrayed as heavy water users, competing with already scarce resources to cool their infrastructure. This perception is now firmly established. It is also, to a large extent, misleading.

The question seems straightforward: do data centers consume too much water? In reality, it is far more complex. Recent life-cycle assessments (LCAs) carried out on European infrastructure are reshaping the debate. They show that both the scale and the location of water impacts are widely misunderstood. Two identical data centers, built in different countries, can have significantly different water footprints.

Direct water consumption: A limited part of the picture

One finding stands out. In a data center powered by renewable electricity and using closed-loop cooling systems, on-site water consumption represents less than 0.1% of total water impact.

In other words, the metric most frequently discussed in public debate is also the least significant. The vast majority of water impact occurs elsewhere, in the production of materials and, above all, in electricity generation.

Electricity production: The real driver of water impact

The true water footprint of a data center is largely determined upstream, by the way electricity is produced.

In France, for instance, more than half of a data center’s total water footprint can be attributed to its operational phase, driven primarily by electricity production rather than cooling itself.

This observation is context-specific. It highlights a broader issue: water impact depends on variables that the public debate often overlooks.

Location matters more than expected

Three key factors fundamentally shape a data center’s water footprint.

The first is the national energy mix. In countries where electricity is generated from thermal power plants, water is consumed in large quantities for steam production and cooling processes. In nuclear-based systems, such as in France, the dynamics differ but remain significant.

The second factor is geography. Life-cycle assessments account for local water scarcity, meaning that one cubic meter of water does not carry the same environmental weight everywhere. Water withdrawal in southern Europe, where resources are more constrained, has a very different impact compared to northern regions where water is more abundant.

The third factor is cooling technology. Not all systems follow the same logic. Some rely on evaporative cooling, which consumes water directly on site. Others, such as closed-loop or dry cooling systems, mostly used in Europe, significantly reduce or eliminate local water use. The relevance of each solution depends heavily on local climate conditions.

The limits of a single metric

The industry has long relied on the water usage effectiveness (WUE) indicator to measure water performance. While useful, this metric only captures on-site consumption and therefore provides a partial view.

At Data4, the continuous improvement of cooling design and water management has led to a 44 percent reduction in WUE since 2021, reflecting a particularly responsible approach to water usage. This performance is notably achieved without the use of cooling towers, which are known for their high-water consumption, and results in WUE levels significantly below typical industry benchmarks.

However, even this type of performance indicator has its limits. A data center can achieve an excellent WUE while operating in a water-stressed region or relying on a water-intensive energy mix. In such cases, the overall environmental impact may still be significant.

This is precisely what life-cycle analysis reveals: water impacts are often displaced rather than reduced.

Towards a more comprehensive approach

Water resources are under increasing pressure globally, while data center capacity continues to expand, driven by artificial intelligence and digital growth.

Addressing this challenge requires a shift in perspective. Measuring water consumption at the facility level is no longer sufficient. A comprehensive approach must consider the full lifecycle, integrating energy production, geography, and climate.

Beyond efficiency improvements, data centers can also become part of broader environmental ecosystems. Initiatives such as Data4’s bio-circular data center project, which reuses waste heat to create new local resources, illustrate the sector’s potential to contribute positively to territorial sustainability.

Only by adopting this broader view can we identify where impacts truly occur and ensure that we are not acting in the wrong place.