Is there a hidden cost to data centre water usage?

Amazon Web Services (AWS) is expanding the use recycled water for cooling to 120 of its data centres as part of its goal to be water positive by 2030, a milestone it is 53 per cent of the way to achieving. However, with the rapid expansion of data centres being built to meet the demands of AI, is there a question over whether AWS and its peers water positive efforts can keep up with their own growth?

 

Expanding use of water recycling

Previously, AWS had been using recycled water at 24 data centres. The company announced that by expanding water recycling to a further 100 centres it would preserve over 530 millions gallons of drinking water in the communities in which it operates. At present, the expansion is limited to the company’s data centres in the US.

Announcing the expansion, Kevin Miller, vice president of global data centres for AWS, told media: “We are deeply committed to being good members of our communities, and doubling down on preserving freshwater resources is one of the ways we can demonstrate that.”

He added: “By significantly expanding our recycled-water infrastructure, we’re aiming to advance technological innovation while still prioritising environmental stewardship.”

 

Evaporative cooling systems and wastewater

AWS has stated that it’s preference would be to use no water in its data centres, but accepts that there is still a need. The company has, however, reduced its annual water use in data centres by 85 per cent by using direct evaporative cooling systems (compared to traditional systems).

These systems pull hot air from outside and push it through water-soaked cooling pads. The water evaporates and cools the temperature of the air sent to the server rooms. By using recycled water with direct evaporative cooling, the company has a greatly reduced need to use potable water.

In Virginia, USA, the company became the first data centre operator in the state approved to use recycled water with direct evaporative cooling systems. This is significant because northern Virginia can claim to be the data centre capital of the world with more than 300 centres processing as much as 70 per cent of global digital information. In 2023, AWS invested €30.5 billion in the area, a year later, Google spent €874 million upgrading three facilities.

In areas where the climate allows, AWS is combining evaporative cooling with free-air cooling systems which use no water, only turning the evaporative system on when needed. AWS reports that in countries like Ireland and Sweden, this combined system has led to no water being needed to cool its data centres for 95 per cent of the year.

 

Water recycling and wider replenishment goals

The company has committed to becoming water positive by 2030. Reporting annually on its efforts, data for 2024 suggests AWS has achieved 53 per cent of its target of returning more water to communities than it uses in its direct operations.

To do this it has addressed efficiencies in its own operations, such as its water recycling use in data centres, as well as implementing water recycling initiatives in its corporate offices, such rainwater capture, reusing shower water, and more. It has also scaled harvesting and reuse solutions in its fulfilment centres, sort centres, and delivery stations around the world.

Replenishment is a major contributor to the company’s water positive goals. AWS partners with many other organisations and local stakeholders and community groups to work on replenishment projects in the areas of the world in which the company operates.

 

Conserving water in a rapidly expanding cloud

A major challenge for AWS will come from the rapid expansion of data centres around the world as it seeks to meet demand for cloud services and AI-processing. Amazon plans to invest approximately €87 billion in data centres in the 10 years to 2035. With major players like Google, Microsoft and Cyrus One all planning further expansion, the issue of water use will only increase.

Each of these companies has announced sustainability goals that include water targets. And while Apple has committed to expanding its water targets to its supply chain, Cyrus One, has gone one step further by including the water used in electricity generation in its targets.

 

The hidden water cost of data centres

While every effort to conserve and reuse water is both necessary and worth acknowledging and pursuing, there is a feeling that without data centres being powered by 100 per cent renewable energy, the true cost of water is not being measured by the big data centre operators.

Cyrus One’s 2024 sustainability report addresses this directly: “We understand that no matter how much we reduce our onsite water consumption, as long as we are reliant on grid electricity, we are indirectly responsible for the consumption of large amounts of water through traditional thermoelectric electrical generation for the foreseeable future.”

This energy production use of water is now a metric against which the company’s goals are measured: “We have begun efforts to quantify this energy supply chain water consumption to understand both our full impact on water resources and the risk of electrical supply disruption due to increased water stress.”

A report on the Grist website highlighted the work of Shaolei Ren, a professor of engineering at the University of California, Riverside, who studies data centre water usage. Ren’s research suggests that water consumption by power plants supplying electricity to data centres can be anywhere between three and 10 times more than by the centre itself.

However, AWS and Amazon have pledged to reach net-zero carbon emissions by 2040, and according to Bloomberg NEF it is consistently the largest corporate purchaser of renewable energy. The company’s drive toward renewable energy can help it reduce the water cost of its data centres further.