Data centre water usage is attracting increasing scrutiny

Rightly, energy efficiency commands the lion’s share of the attention when it comes to data centre sustainability. That does not mean that other environmental issues should be ignored, and the topic of water efficiency presents its own challenges for data centre owners and operators in the age of climate volatility.

Water, water everywhere,

And all the boards did shrink:

Water, water everywhere,

Nor any drop to drink.

More than 200 years ago, the poet Coleridge showed remarkable prescience in writing ‘The Rime of the Ancient Mariner’. Boardrooms up and down the UK wrestle with the threat of potential water shortages, along with increasingly frequent, actual drought events on an island surrounded by the sea. Alas, the sea, unless desalinated, is neither fit to drink, nor to use in industry.

Thames Water opened a desalination plant back in 2010 in Beckton, London. And Southern Water, for example, is planning to build a desalination plant in the Solent to turn seawater into drinking water. While there are certain variables as to the exact costs of producing desalinated water, it’s safe to say that the various available technologies are all more expensive than conventional drinking water treatment.

Desalination may become more prevalent in the UK over time – for now, it tends to be used only in very hot climates, where water scarcity is a major issue. Ah, but as various droughts in the UK – most famously those of 1976 and 1995 – have shown, the UK, despite its rainy reputation, is not awash with water. The problem is especially acute in the south east and East Anglia. And where are many of the UK’s data centres?! So, innovation and better use of existing resources are vital moving forward.

Internationally, predictions that many of the wars of the 21^st century would be fought over (scarce) water resources have not come to pass. But we’re only in 2021, and the fact that many rivers pass through several countries before reaching the sea, means that the potential for water-related conflicts remains (cutting off a water supply via a dam being the likely action).

Apologies for the brief lesson in water resources. I’ve spent much of my writing career immersed in this world, and as a result, I believe that, in the UK at least, owing to the assumption that it ‘rains all the time’, we do not fully understand the dangers we face when it comes to water scarcity.

Against this background, it makes sense for the data centre industry to ensure that it a) understands the issues around what we might call ‘profligate’ water consumption and b) contributes to the national water efficiency drive. Along the way, reduced water consumption or, as with energy, more efficient use of existing or even increased resources, should lead to significant financial savings.

Compared to energy efficiency, data centre water efficiency measurement is in its infancy. There is a Water Usage Efficiency (WUE) metric (and it has been around since 2011), which works along similar lines to PUE. However, where calculating PUE is relatively easy (power in/compute out), WUE is a little more complex. That’s because there are two major types of water consumption to be considered. Firstly, there’s the amount of water required to generate the power which a data centre consumes. Secondly, there’s the water consumed as a function of a facility’s cooling solution.

There is a brilliant article on data centre water consumption in Nature, written by David Mytton in February this year (1). This provides a detailed analysis of current, and increasing levels of data centre water consumption. In terms of the power generation piece, it seems that only wind and solar renewables do not consume water as part of the power generation process. (Although the manufacture of solar panels and wind turbines does). As for the various data centre cooling solutions available, they all require water.

There are different types of water – potable, rain, and waste for example. Treated, potable (drinking) water is the most expensive to use within the data centre. Theoretically, it’s ‘unnecessarily’ clean for use in the data centre, but what are the alternatives?

Rain water could, in theory, be collected via a data centre roof and/or via appropriate drainage technology, but would almost certainly need to be cleaned, or polished, before it could be used as cooling water. This is required to eliminate the possibility of water contaminants damaging the cooling plant over time. Similarly, wastewater can be recycled. Depending on the space constraints, a data centre could install its own wastewater treatment and recycling facility.

Alongside any space issue, there’s also the question of budget and (lack of) expertise. Does a data centre operator also want to build, own and operate a wastewater treatment plant, and have the necessary expertise to run it?

As with so many data centre sustainability issues, when it comes to water consumption, each individual organisation will need to balance environmental, operating and business considerations. What is thought to be the first net positive water data centre was announced just over a year ago (2). I’m not aware of any similar announcements since, which demonstrates how difficult achieving this balance can be.

In finishing, when engaging with a data centre provider, end users would do well to include water Water Usage Effectiveness as part of any sustainability conversation. For now, the focus may well be on energy production and power consumption. Over time, as climate volatility increases, the issue of water supply and demand will increase in importance. Your colocation partner should not shrink from such a discussion, rather welcome the chance to demonstrate their water consumption plan as part of an overall sustainability strategy.

Data centre water consumption | npj Clean Water (nature.com)

Mytton, D. Data centre water consumption. npj Clean Water 4, 11 (2021). https://doi.org/10.1038/s41545-021-00101-w

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