Sustainable Water Use in Data Centers: Balancing Efficiency and Environmental Impact

Sustainable Water Use in Data Centers: Balancing Efficiency and Environmental Impact

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  Data Center WaterUse: Advantages, Disadvantages & Trade-offs Infrastructure Sustainability Research Group July 30, 2026 Abstract The rapid global expansion of cloud computing and artificial intelligence (AI) work- loads has driven an unprecedented surge in data center construction and rack power densities. While the energy consumption of these facilities has received extensive scholarly and mainstream scrutiny, their water footprint—comprising direct on-site cooling and indirect off-site power generation—remains complex and heavily debated. This paper provides an evidence-based synthesis of data center water consumption, evaluating the thermodynamic advantages of water-based cooling, the localized dis- advantages of consumptive loss and environmental justice concerns, and the critical water-energy trade-off. We review standardized metrics including ISO/IEC 30134-9 Wa- ter Usage Effectiveness (WUE), convective heat transfer coefficients (HTC), and spatial- temporal frameworks for sustainable infrastructure design. 1 Introduction and Context Global digitalization and the exponential scaling of generative AI models have intensi- fied computing infrastructure expansion. Data centers serve as the physical backbone of the digital economy, housing servers that convert electrical energy into computation and, consequently, large volumes of heat. To maintain operating temperatures within reliability limits, facilities must dissipate substantial thermal loads. While direct electricity use regularly receives coverage, water consumption has emerged as an equally critical sustainability dimension. According to Lawrence Berkeley National Laboratory (LBNL) reports, direct on-site water consumption by U.S. data centers reached approximately 66 billion liters in 2023, representing a nearly 200% increase over a decade (21.2 billion liters in 2014). When incorporating off-site power plant water requirements for thermoelectric electricity generation, total U.S. data center water use scales to approximately 560 billion liters annually. 2 Water Consumption Boundaries: Direct vs. Indirect Data center water footprints are divided into two distinct operational scopes: - Direct / Scope 1 Water (On-Site): Water withdrawn and consumed on-site for cli- mate control and equipment cooling. Open evaporative cooling towers utilize the latent heat of vaporization (≈ 2, 260 kJ/kg) to reject heat into the atmosphere. Ap- proximately 70% to 80% of withdrawn water is lost permanently via evaporation, requiring continuous municipal replenishment—frequently using potable drinking water to prevent mineral scaling. 1
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  Data Center WaterResearch Report HyScaler.com - Indirect / Scope 2 Water (Off-Site): Water consumed upstream at thermoelectric power plants (coal, natural gas, nuclear) to generate the electricity required by the facility. Thermoelectric power generation in the U.S. averages between 1.25 and 2.18 L/kWh of consumption, with coal generation withdrawal rates reaching up to 132.5 L/kWh. Consequently, indirect grid water consumption frequently exceeds di- rect facility water use by 3× to 20×. 3 Measurement Standards: Key Performance Indicators To quantify water efficiency, the industry utilizes standardized Key Performance Indicators (KPIs) established by The Green Grid and standardized under ISO/IEC 30134-9: WUE = Annual Site Water Usage (Liters) IT Equipment Energy Usage (kWh) (1) Units are expressed as L/kWh (or m3/MWh), where an ideal on-site WUEsite = 0.0. To capture lifecycle impacts, the extended metric WUEsource incorporates both on-site facil- ity water and off-site power generation water intensity. Furthermore, the Climate Neu- tral Data Centre Pact (CNDCP) establishes strict regional limits for new facilities in water- stressed areas: WUEmax = 0.40 L/kWh. 4 Advantages of Water-Based Cooling Water-based thermal management provides distinct thermodynamic and economic ben- efits: - Superior Heat Capacity: Water’s high latent heat of vaporization enables phase- change cooling that absorbs massive thermal loads without elevating server room ambient temperatures. - Energy Efficiency Gains (PUE Reduction): On-site evaporative cooling reduces compressor chiller workloads, lowering overall facility energy consumption by 10% to 15% compared to dry air-cooled systems. - CapEx and OpEx Savings: Operating chiller supply water at warmer temperatures (18–20◦C vs. traditional 7–10◦C) cuts mechanical chilling operational expenses by up to 40% and reduces initial capital expenditure on chiller sizing by 30%. 5 Disadvantages and Localized Impacts Despite operational efficiencies, water-intensive cooling architectures present substantial drawbacks: - Consumptive Watershed Depletion: Unlike domestic water use where wastewater is treated and returned, evaporative cooling permanently removes water from local hydrological basins. - Potable Water Competition: Facilities frequently rely on municipal drinking wa- ter infrastructure, creating direct competition with local residential and agricultural communities during drought conditions. 2
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  Data Center WaterResearch Report HyScaler.com - Chemical and Thermal Pollution: Cooling tower blowdown discharges chemical additives (biocides, anti-scalants, corrosion inhibitors) and warm water into local aquatic ecosystems. - Environmental Justice Concerns: Recent research highlights that hyperscale facil- ities are frequently sited in socio-economically vulnerable ex-urban regions facing severe groundwater stress. 6 The Core Dilemma: The Water vs. Energy Trade-off A fundamental inverse relationship exists between data center water and energy con- sumption. Transitioning to waterless dry-cooling systems eliminates direct on-site water consumption (WUEsite = 0), but forces mechanical chillers and massive fan arrays to work harder, increasing facility power draw and worsening Power Usage Effectiveness (PUE from ∼ 1.15 up to 1.60). On carbon- and water-intensive fossil fuel electric grids, this surge in off-site electric- ity generation can result in a net increase in total lifecycle water consumption—a phe- nomenon known as the “water shifting” paradox. 7 Cooling Technology Matrix Cooling Topology WUE Range Typical PUE Primary Advantages Primary D Direct Air / Chiller 0.00 L/kWh 1.30–1.60 Zero direct water use; simple. High elec Evaporative Tower 1.20–2.50 L/kWh 1.10–1.20 Lowest facility energy draw. High cons Hybrid / Adiabatic 0.10–0.60 L/kWh 1.15–1.25 Water spray only during peak heat. Requires Direct Cold Plate 0.00–0.20 L/kWh 1.05–1.15 Direct chip contact; >40kW racks. Higher Ca Immersion (1/2-PIC) ∼ 0.00 L/kWh 1.02–1.08 Highest HTC; near-zero water. Fluid cost Table 1: Comparative evaluation of data center cooling topologies across water, energy, and operational dimensions. 8 Conclusion and Policy Recommendations Managing data center water sustainability requires a holistic, systems-level approach that evaluates water and energy simultaneously rather than in isolation. Key policy and engi- neering recommendations include: 1. Mandatory Dual Reporting: Require transparent site-level public disclosure of both Scope 1 (WUEsite) and Scope 2 (WUEsource) metrics under ISO/IEC 30134-9. 2. Transition to Non-Potable Water: Mandate the use of reclaimed municipal wastew- ater effluent or greywater for evaporative cooling in water-stressed basins. 3. Direct Liquid Cooling Adoption: Scale direct-to-chip cold plate and immersion tech- nologies for high-density AI workloads to enable dry heat rejection. 4. Spatial-Temporal Workload Optimization: Utilize frameworks like SCARF to sched- ule non-real-time AI training tasks in regions and hours characterized by low water stress and zero-water renewable energy. 3
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  Data Center WaterResearch Report HyScaler.com References [1] Mytton, D. (2021). Data centre water consumption. npj Clean Water, 4(11). [2] Lei, N., Lu, J., Shehabi, A., & Masanet, E. (2025). The water use of data center workloads: A review and assessment of key determinants. Resources, Conservation and Recycling, 219, 108310. [3] Shehabi, A., et al. (2024). 2024 United States Data Center Energy Usage Report. Lawrence Berkeley National Laboratory. [4] Cooper, A., & Nguyen, T. B. T. (2026). A Review of Thermal Management in Modern Data Centres: Water Usage Effectiveness and Heat Transfer Coefficients. Preprints.org. [5] Wu, Y., Hua, I., & Ding, Y. (2025). Not All Water Consumption Is Equal: A Water Stress Weighted Metric for Sustainable Computing (SCARF Framework). arXiv preprint arXiv:2506.22773. [6] ISO/IEC 30134-9:2022. Information technology — Data centres key performance indicators — Part 9: Water usage effectiveness (WUE). 4