An empirical assessment of data center sites using reclaimed municipal wastewater for cooling
With recent growth in the data center industry has come increasing scrutiny about direct water use in these facilities [1]. Data center water use varies by facility type, location, and operational choices [2, 3]. These facilities use water because it’s usually more energy efficient to cool computing equipment using water than air.
All water use is not created equal. Some facilities use potable water for cooling, some use surface water or groundwater, and some use recycled water, often reclaimed from municipal wastewater. The environmental effects of data centers using reclaimed municipal wastewater (hereafter “reclaimed water”) are much smaller than using other water sources, and this strategy is becoming more widely used. The widespread availability of municipal wastewater treatment infrastructure in cities around the world makes reclaimed water a practical solution that can be implemented in many locations, supporting the global expansion of sustainable data center operations.
This blog post summarizes a brief white paper assessing the prevalence of reclaimed municipal wastewater for data center cooling, focusing on the operations of the top ten companies as assessed by Data Centre Magazine in 2025 (listed in alphabetical order): AWS (Amazon), CyrusOne, Digital Realty, Equinix, GDS, Google, Meta, Microsoft Azure, NTT, and Telehouse. For facilities owned by one company housing computers owned by another company, we ignored the owners of the computing equipment and assigned each facility to its owner/operator.
There is relatively little public data about reclaimed water use for data center cooling, so Zachary Schmidt and I identified publicly available sources from which we could reliably infer the presence or absence of reclaimed water use by facilities owned by these companies around the world. We rely on published reports, news releases, news reports, data center mapping websites, utility bills, utility contracts, conference presentations, and satellite imagery to substantiate the findings. The report links to our sources.
Figure 1 contains the results. As of December 2025, Amazon has the highest number of confirmed sites using reclaimed water for cooling, at 24, with two other companies following with 17 and 13 facilities. Three other companies have between 6 and 8 facilities, with the rest at zero or one facility using reclaimed water. Note that some facilities not using reclaimed water don’t use ANY water onsite for cooling, but that choice generally means cooling for these facilities is less energy efficient than it would be if onsite water were used.
Figure 1: Global tally of data center sites using reclaimed municipal wastewater for cooling
More work is needed to identify locations for which there is no current public information about their use of reclaimed water. Companies using reclaimed water should be happy to publicize it, so we think our relative rank order is unlikely to change much with the addition of new information, but we hope the tally will increase over time. We encourage all data center companies to consider the use of reclaimed water for cooling, as concern over water used by data centers continues to increase.
To download the report, click here.
We are grateful to Amazon Web Services for funding this research.
REFERENCES
1. Shehabi, Arman, Sarah Josephine Smith, Alex Hubbard, Alexander Newkirk, Nuoa Lei, Md AbuBakar Siddik, Billie Holecek, Jonathan G Koomey, Eric R Masanet, and Dale A Sartor. 2024. 2024 United States Data Center Energy Usage Report. Lawrence Berkeley National Laboratory. LBNL-2001637. December 19. [https://eta-publications.lbl.gov/publications/2024-lbnl-data-center-energy-usage-report]
2. Lei, Nuoa, and Eric Masanet. 2022. "Climate- and technology-specific PUE and WUE estimations for U.S. data centers using a hybrid statistical and thermodynamics-based approach." Resources, Conservation and Recycling. vol. 182, 2022/07/01/. pp. 106323. [https://www.sciencedirect.com/science/article/pii/S0921344922001719]
3. Lei, Nuoa, Jun Lu, Arman Shehabi, and Eric Masanet. 2025. "The water use of data center workloads: A review and assessment of key determinants." Resources, Conservation and Recycling. vol. 219, 2025/06/01/. pp. 108310. [https://www.sciencedirect.com/science/article/pii/S0921344925001892]
