It's well known that data centers use enormous amounts of electricity. What's not as obvious is that many data centers also use enormous amounts of water. As the industry has intensified its focus on energy efficiency, many of the largest data center providers have also taken steps to address their use of water.
Awareness of data center water usage is likely to gain a higher profile as environmental groups and investor advocates push for increased disclosure of corporate water usage. An example: The Carbon Disclosure Project, which has persuaded some of the world’s largest corporations to disclose their greenhouse gas emissions, is announcing a program to press public companies to also issue detailed reports on their water use, according to The New York Times. The move "begins a campaign to put water consumption on par with carbon emissions as a concern of company shareholders."
The enormous volume of water required to cool high-density server farms is making water management a growing priority for data center operators. A 15-megawatt data center can use up to 360,000 gallons of water a day, according to one estimate.
Why do data centers use so much water? The move to cloud computing is concentrating enormous computing power in mega-data centers containing hundreds of thousands of servers. All the heat from those servers is managed through cooling towers, where hot waste water from the data center is cooled, with the heat being removed through evaporation. Most of the water that remains is returned to the data center cooling system, while some is drained out of the system to remove any sediment, a process known as blowdown. (See Data Centers Move to Cut Water Waste for more details.)
When this process is played out at mega-data center scale, the amount of water required for cooling can be enormous, sometimes exceeding the capacity of local utilities. The city of Northlake, Ill. expanded its water capacity to support Microsoft’s massive new Chicago data center.
In other instances huge data centers have taken steps to address their water usage and impact on local utilities.
Google is notable among industry companies for its steps to reduce water usage. Two of its data centers run entirely on recycled water (as does Microsoft's San Antonio data center). Google also uses water from a nearby industrial canal to cool its data center in Ghislain, Belgium. The company has built a 20,000 square foot water treatment plant to prepare the canal water for use in its nearby data center.