Climate change and datacentres: Weighing up water use

Discussions about datacentre sustainability tend to focus on what can be done to make facilities more energy-efficient and less reliant on fossil fuels, as operators look to curb their greenhouse gas emissions and become climate-neutral.

Against a backdrop of heightening concerns from regulators and government policymakers about the contributory role datacentres may play in the onset of climate change, operators have had no choice but to become more transparent about the type and amount of power they use.

Also, datacentre operators are increasingly being called upon to make their sustainability initiatives more inclusive by tracking the use of a broader range of resources that are consumed and generated during the entire lifecycle of their server farms.

This is a theme that the UK’s Department for Environment, Food and Rural Affairs (Defra) touched on in its October 2019 guide to what businesses can do to make their ICT strategies and technology supply chains more sustainable.

One of the recommendations in the Defra document was a request for IT leaders to monitor and reduce the size of the ecological footprint of their entire ICT estates, including their datacentres and the servers they contain.

Doing so would provide a much clearer and more accurate view of the true environmental impact that datacentres have, says the document, before calling on server farm operators to track the amount of water their sites consume more closely than they do currently.

“Water usage is a major factor in the operation of datacentres and is used both to maintain the operating environment [temperature] of the facilities, and to operate the ICT equipment contained in them,” says the report.

And with water on course to become an increasingly scarce resource within the next decade, pressure is growing on datacentre operators to apply the same level of commitment to conserving water as they currently do to ensuring their sites are energy-efficient.

And for good reason. The United Nations predicts that demand for fresh water will exceed supply by 40% within the next decade due to a combination of population growth and climate change-related global warming and drought.

Meanwhile, the Massachusetts Institute of Technology forecasts that 52% of the world’s projected 9.7 billion people will live in water-stressed areas by 2050.

Predictions such as these are being drawn to the attention of datacentre operators relying on evaporative and adiabatic cooling systems to regulate the temperature of their facilities, especially if they run server farms in areas of the world that are already prone to drought.

“A medium-sized datacentre (15MW) uses as much water as three average-sized hospitals or more than two 18-hole golf courses”

David Mytton, Uptime Institute

At the time of writing, the US state of California was in the midst of a historically bad and prolonged period of drought that saw the county of Santa Clara, which is reportedly home to more than 40 datacentres, hit with mandatory water restrictions in June 2021.

What is concerning about this is that most of the water used by datacentres typically comes from potable sources that supply homes and businesses with drinking water, which in times of drought could have dire implications for the local community.  

“Datacentres compete with other users for access to local resources,” wrote David Mytton, a sustainable computing-focused research affiliate with the Uptime Institute, in a February 2021 article for the journal Nature. “A medium-sized datacentre (15MW) uses as much water as three average-sized hospitals or more than two 18-hole golf courses.

“Some progress has been made with using recycled and non-potable water, but from limited [industry] figures available, some datacentre operations are drawing more than half of their water from potable sources.”

How much of an issue that poses depends on whether the datacentre in question is sited in an area prone to water stress, Mytton tells Computer Weekly in a follow-up interview. “If you put your datacentre next to a source of abundant water, then its water [usage] isn’t really a concern, but if you are putting your datacentre into a region that has a high water stress, then it does become an issue,” he says.

Knock-on impact

Consulting datacentre engineer Ian Bitterlin says datacentre location also tends to dictate what kind of cooling method an operator will favour, which can also have a knock-on impact on how much water a site consumes.

“Water consumption is very high in North America and anywhere else that uses wet cooling towers,” he tells Computer Weekly. “In Europe, we generally don’t use wet cooling towers – so water consumption is very low, and the adoption of evaporative and adiabatic cooling systems [within the continent] has been slower and is likely to remain so.”

One of the reasons for that is historical biases and preferences by operators across Europe for datacentres that rely on less water-intensive, air-cooled designs, says Bitterlin.

In the UK, specifically, operators are not keen on using wet cooling towers as part of their datacentre cooling setups because of health and safety concerns, he adds.  

“There is a long history in the UK of a perceived link between water towers and legionella outbreaks and the threat of having your data facility shut down because a water-based cooling tower plant is found to contain legionella bacteria is generally regarded as an unacceptable risk,” says Bitterlin.

For example, he points to the 2012 outbreak of legionnaire’s disease in Edinburgh that resulted in 92 deaths and led to “key datacentres” for several Scotland-based financial services firms, including the Royal Bank of Scotland, Standard Life and Scottish Equitable, being shut down.

As important as location is, that does not mean datacentre operators with sites in areas where potable water is in plentiful supply now can afford to ignore the need for water conservation, as the Uptime Institute warns in its 2020 Global datacentre survey.

“In a water-scarce future, it is not enough to just move or site datacentres in regions with adequate water supplies”

Uptime Institute report

The onset of climate change, and the transformational impact it is already having on the world’s weather patterns, means that areas that are not currently affected by drought could be within the average lifespan of a datacentre.

“In a water-scarce future, it is not enough to just move or site datacentres in regions with adequate water supplies,” says the report. “Changes in climate and population growth can cause those regions to become water-stressed in coming decades – certainly during a facility’s lifespan.”

A separate Uptime Institute report, published in late 2020, about the impact climate change will have on the resilience of the datacentre industry details further the threat that water shortages could pose to the growth potential of operators in years to come.

The report cites Singapore as a cautionary example of a datacentre hub whose growth has led to a “significant tightening” of the nation’s planning laws to safeguard energy and water supplies for the local population.

“Shortages of water are a major issue in datacentre hubs in California, Singapore, Spain, the United Arab Emirates, Australia and, periodically, in many other regions of the world,” says the Uptime Institute report.

“In Europe, Spanish planning authorities are concerned over the use of water-intensive cooling and may restrict the use of systems that consume too much water. New builders may face legal challenges as they try to negotiate guaranteed water supplies.”

Feeling the pressure

And it is not just Spanish datacentres that are feeling the pressure – European operators that join the Climate Neutral Data Centre Pact (CNDCP) are also being urged to become more mindful of the water usage habits of their datacentres.

The CNDCP was launched in January 2021 to challenge Europe’s server farm operators to become climate-neutral by 2030 and includes a requirement for participants to take steps to reduce the amount of water their sites use.

Participants in the pact, which include Amazon Web Services, Google, Equinix and CyrusOne, to name a few, will be set annualised water conservation targets from 2022 onwards, which must be met by new datacentres by 2025 and existing ones by 2030. 

In a policy paper submitted to the European Commission in June 2021, the CNDCP says it plans to go public later this year with the metric it will use to assess water conservation, which will include a “careful consideration” of all the “interacting factors” that influence how much water datacentres consume for cooling purposes.

“Different datacentre designs rely on different cooling techniques that must consider the region, climate, resources and most sustainable cooling method,” says the policy paper.

The paper also details other steps that datacentre operators should consider taking to minimise the amount of potable water they use to keep their sites cool.

“Datacentres that use water can prioritise the use of industrial water where suitable, and reduce the use of potable water for cooling, employing sustainable on-site treatment technologies to reuse water and develop partnerships with local water facilities to reuse industrial water,” it adds.

How much water do datacentres use?    

As detailed in the research paper A circular economy for the data centre industry, published in June 2021, it is estimated that the datacentre sector consumes enough water for cooling purposes to fill 120,000 Olympic-sized swimming pools each year.

But apart from cooling, a sizeable amount of water is also used to generate the energy – particularly where fossil fuel-based forms of power are concerned – used to power datacentres, says the Uptime Institute’s Mytton.

This is a fact that operators often choose to ignore, but it is one they need to acknowledge if they are serious about getting an accurate picture of the true environmental impact their operations have, he says.

“Most datacentre operators consider the water consumption from electricity to be outside the scope of their environmental strategy and environment impact, but that is the wrong way to look at it,” says Mytton.

“Datacentre operators need to be thinking about their environmental impacts, not just the first-order effects of the direct datacentre consumption [of water] from cooling, but also the indirect effects from the water consumed in power generation.”

“Most datacentre operators consider the water consumption from electricity to be outside the scope of their environmental strategy and environment impact, but that is the wrong way to look at it”

David Mytton, Uptime Institute

This is why ramping up their use of renewable power – particularly solar and wind – is such an important move for datacentre operators, because it will allow them to indirectly curb their water consumption while lowering their carbon emissions, says Mytton.

“This means they [operators] need to move to renewable sources as quickly as they can,” he adds.

In a similar vein, ensuring that their facilities use power in the most efficient way possible will contribute to keeping in check the amount of water that datacentres consume, says Mytton.

The past 18 months have seen many of the major colocation providers, including Equinix, Digital Realty and CyrusOne, go public with sustainability pledges to ramp up their use of renewable power and curb their carbon emissions.

The big three hyperscale cloud providers, Amazon, Google and Microsoft, have also previously publicly committed to transitioning to renewable power sources to run their server farms.

Such initiatives are a step in the right direction when it comes to datacentre water conservation, but it is hard to get a real handle on how much difference it will make because very few datacentre operators publicly disclose how much water is used in their sites.

There is also very little consistency across the industry in how operators record and report their water consumption figures, which makes it difficult to get a clear view of what is going on, says Mytton.

Datacentre efficiency consortium The Green Grid introduced the Water Usage Effectiveness (WUE) metric a decade ago as a way for operators to keep tabs on how much water their sites use, while also making it easier for them to pinpoint areas where improvements could be made.

The Green Grid previously pioneered the Power Usage Effectiveness (PUE) metric as a means for operators to measure the energy-efficiency of their facilities, which has since been broadly adopted across the datacentre industry.

Operators regularly tout in their marketing materials any year-on-year improvements in PUE that their sites have seen, but WUE scores rarely feature so prominently, says Mytton. “Facebook use it, and they publish their WUE numbers, but nobody else on their scale does,” he points out.

On this point, Computer Weekly contacted AWS, Google and Microsoft for details on how they monitor the water used in their hyperscale cloud facilities.

Google says it does not provide a site-by-site breakdown of the water consumed by its datacentres. AWS did not directly respond to the question, although Computer Weekly understands the firm does use its own in-house metrics to monitor the water efficiency of its sites.

Microsoft, meanwhile, confirmed that it does use the WUE metric to monitor the amount of water its datacentres consume, but does not publicly disclose its scores.

“In our datacentres, we measure Water Usage Effectiveness (WUE) in combination with cooling method and local climate to measure and project water use in our datacentres as water is needed,” a Microsoft spokesperson tells Computer Weekly.

Based on Mytton’s own research and experience, he says Microsoft is the best of the “big three” when it comes to providing IT buyers with some degree of transparency into the water usage habits of its datacentres – but they could all afford to do more than they do at present.

“Microsoft does provide source breakdowns and regional breakdowns [on its water use], which makes it easier for users to understand the environmental impact if they opt to use Microsoft Azure, for example,” says Mytton. “But if no other providers publish that data, there’s nothing to compare it to.”

Room for improvement

The results of the Uptime Institute’s 2020 Global datacentre survey also shone a light on how patchy the reporting of water usage is across the datacentre industry generally.

Drawing responses from 846 datacentre operator-level respondents from around the world, just half of those said their organisations monitored the water used by their datacentres and wider IT operations.

“Many large datacentre operators have stepped up their efforts to conserve water during the past decade, but progress across the industry has generally been slow,” says the report.

“Some of the largest datacentre owners have only recently begun collecting comprehensive water usage data across their portfolios; others are still working to do so.”

One reason for this slow progress could be that it is harder for operators to get to grips with how to run their sites in a more sustainable way from a water consumption perspective, says Mytton.

From an energy usage point of view, for example, the actions that operators need to take to make their sites more sustainable are relatively straightforward and easy to understand.

“With energy, the goal is to transition to renewable sources of energy generation and work towards net-zero carbon emissions, or negative carbon emissions,” he says. “It is a very simple goal – you have either achieved it or you haven’t. With water, it is more complicated to understand what operators should be aiming for.”

Another factor to bear in mind is that, historically speaking, a lot of datacentres have sought to lower their PUE scores by shifting away from using more energy-intensive mechanical cooling systems to ones that rely on evaporation and, in turn, consume a lot of water.

It is therefore possible that there might be reluctance among some operators to go public with their WUE scores because it might reveal that their PUE has been achieved by consuming large quantities of water, says Mytton. But how problematic that is depends on several factors.

“You’d need to know the source water consumption to decide if increasing water on-site is worth it for the reduced energy consumption because that may mean less water used in the electricity generation, so less water overall,” he adds. “This is why WUE is important to measure on both site and source, so you can consider the full context.”

As previously discussed, datacentre location will influence the water conservation strategy of a datacentre, along with how it is powered and cooled, he says.

“With water [compared to energy], the discussions get more nuanced, because a datacentre that consumes zero water sounds like it should be the goal, but it’s context-specific depending on the location,” he says.

“Most server farms are built to last 20-25 years, so what happens if you have a five-year-old site that has not been designed necessarily to prioritise water conservation?”

Tony Lock, Freeform Dynamics

“What you have is this multifaceted conversation about where is the datacentre, and what is the [locational] context of that specific facility, and how is that going to change over time [with climate change]? Also, what resources is it drawing on from the electricity grid and what does that mean for the water consumption?”

Another complicating factor in all of this is that the average lifespan of a datacentre is 20-25 years, and it is unclear how many of the server farms in operation today will have been designed with water conservation in mind, says Tony Lock, distinguished analyst with IT market watcher Freeform Dynamics.

“It will take time for the industry to adapt,” Lock tells Computer Weekly. “Most server farms are built to last 20-25 years, so what happens if you have a five-year-old site that has not been designed to prioritise water conservation? 

“Existing sites will need significant upgrades, but you can’t take them offline for a year or however long to rebuild them, and that presents a challenge to the datacentre industry.”

But as complicated and challenging as the prospect of cutting the amount of water datacentres use might seem, it is imperative that the facilities get to grips with this issue sooner rather than later, says Lock.

“The association between power usage, carbon emissions and environmental-friendliness is well ingrained in people’s minds, but the role of water in that is not. And it’s an association – at the moment – that is really only being talked about in research papers,” he says.

“As the effects of climate change become ever more visible, that will contribute to raising awareness among the general public about the scarcity of water, and why more needs to be done to conserve supplies of it in water-stressed regions, specifically,” adds Lock.

“In the same way, four or five years ago, attention started to be drawn to the carbon footprints generated by flights and airlines. That led to more attention being paid to the energy use and carbon emissions of datacentres. That’s not happened for water yet – but it will,” he says.


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