In the twenty-first century, data centres are critical infrastructure. They power the cloud computing services we all rely on for everyday life – from banking to navigation. But data centres also have a reputation for consuming huge volumes of water. So how can we ensure that they don’t contribute to water scarcity? 

A data centre’s total water footprint includes the water used on-site for various purposes like cooling, plumbing, landscaping, and fire suppression, as well as the water used off-site at a power plant to generate the electricity required for the facility. But they still draw substantial volumes of potable (drinking-quality) water from their local watershed, a significant proportion of which is lost to evaporation and during storage and treatment. 
How much water are we talking about? Take, for example, a typical small one-megawatt data centre that uses traditional cooling methods. It would consume more than 26 million litres of water each year – enough to supply over 200 UK homes. So, what can data centre operators do to cut their water consumption?

View water systems as circular, not linear

Most operators focus initially on improving water-use efficiency (WUE) in their cooling systems. At Arup, we think it’s time to consider the water system as a whole – the ‘One Water’ concept. Each litre that a data centre abstracts from within its watershed is either evaporated, reused, or returned to that watershed to go around again. So, thinking about the entire process as circular is more helpful than viewing supply and discharge as separate systems. 

Matching solutions to the local area

When planning a new data centre, the most critical factor is location. Could you avoid watersheds that suffer droughts and opt instead for a site where water is plentiful? Have you studied the nearest water source and estimated how much you expect to draw from this? Carrying out due diligence and considering factors such as these can ensure that the data centre will not exacerbate issues of water scarcity in the area.  

Switching the water supply to reclaimed, specifically treated municipal wastewater that can be reused, rather than potable water can also make a significant difference. By utilising advanced treatment processes wastewater generated on site, wastewater can be reused across site, significantly reducing raw water abstraction.  Alternatively, you could situate a data centre near a municipal sewage treatment facility, it may have the opportunity to directly utilise the final effluent, treated and clarified wastewater discharged from the sewage works.

Both new and existing data centres can incorporate rainwater harvesting features, such as blue roofs to collect and store rainwater. Re-using rainwater reduces local flooding, cuts costs, and protects against future water shortages. Smart water storage is another useful consideration. It enables you to predict demand and store just the right amount of water, rather than building and maintaining excessive storage.

As well as looking for opportunities to take less water from the watershed, you can also make smarter use of water through joined-up thinking. We recently worked with a client to locate a data centre close to a food factory that requires large volumes of high-salinity water. This is exactly what the data centre discharges, so instead of treating the water it could pass it on to the food factory and both companies could benefit. Partnering with energy companies that use cooling towers can also generate synergies.  

Wherever water is sourced from, there are established solutions for recovering, treating and re-using it on site. This approach is used widely by our clients in the food and beverage industries, and their systems can be adapted for data centres. It can also be a good option where there are restrictions on the use of chemicals for water treatment.

Be prepared for change

Many of our data centre clients are already taking steps like this. And because the regulatory landscape in this area is changing quickly, many more are exploring the possibilities. In our experience, it’s best to talk directly to stakeholders early – including regulators and planning authorities –to find out what is likely to be required, as well as thinking about what might be possible. 

Alongside regulatory change, there is also the pressing consideration of climate change.  

Operators should consider how they could invest directly into the same watershed through local projects, led by local organisations. Restoring ponds and natural wetlands or improving soil and vegetation will help to minimise impact for local residents and wildlife and could also contribute to biodiversity net gain. 

Ultimately, no matter how innovative or water-efficient a data centre is designed to be, it’s the operation that matters. Commissioning, training operators and maintaining systems are all just as critical as the location and the design. Continuous monitoring water of consumption combined with regular reviews and maintenance will keep systems as efficient and resilient as possible. 

Taken together, these steps can ensure that data centres don’t add to the problem of water stress – and can even be part of the solution. 

Article based on contributions from Chelsea Merrick