Data Management Glossary
Water Usage Effectiveness (WUE)
Water Usage Effectiveness (WUE)
Water Usage Effectiveness (WUE) is a data center sustainability metric that measures how much water a facility consumes per kilowatt-hour of IT equipment energy use. The Green Grid developed WUE alongside Power Usage Effectiveness (PUE), applying the same logic to water instead of electricity. A lower WUE means a data center uses less water to support the same amount of computing work.
The WUE formula
WUE = Data center water consumption in liters divided by IT equipment energy use in kilowatt-hours
Water consumption includes direct use, mainly cooling towers and evaporative cooling systems, plus indirect use tied to the electricity generation that powers the facility. Most enterprise data centers land between 0.2 and 1.8 liters per kilowatt-hour depending on climate, cooling design and water reuse practices.
WUE is derived from the concept of Power Usage Effectiveness (PUE) and Carbon Usage Effectiveness (CUE), which focus on energy efficiency and carbon emissions, respectively. Just as PUE and CUE aim to minimize energy consumption and carbon footprint, WUE aims to minimize water consumption and promote sustainable water management in data centers.
To calculate WUE, the total water consumption of a data center is divided by the amount of computing work or IT equipment output. Water consumption includes both direct water usage, such as for cooling systems, and indirect water usage associated with electricity generation.
WUE = Data center water consumption (L) ÷ IT equipment energy usage (kWh)
By optimizing cooling systems, adopting water-efficient technologies, and implementing best practices, data centers can reduce their WUE and minimize their impact on water resources. Strategies for improving WUE may include using water-efficient cooling methods, recycling and reusing water, implementing advanced cooling technologies like evaporative cooling, and optimizing facility design for reduced water usage.
Efficient water management in data centers is becoming increasingly important as water scarcity and conservation efforts gain attention worldwide. By monitoring and improving WUE, data center operators can contribute to sustainable water use and reduce the environmental impact of their operations.
Komprise has written about the opportunity for sustainable data management as part of an overall sustainability and data center emission, data center optimization and data center consolidation strategy.
Why storage growth affects WUE
Unstructured data growth drives storage growth, and storage growth drives cooling load. Every additional drive, file server or storage array a data center runs adds heat that has to be dissipated, and most enterprise cooling still relies on water-intensive evaporative systems. U.S. data centers directly consumed 17.4 billion gallons of water in 2023, and that figure is projected to reach 38 billion to 73 billion gallons by 2028 as AI infrastructure expands. Source: MOST Policy Initiative, citing the U.S. Environmental Protection Agency and Lawrence Berkeley National Laboratory.
The strain isn’t evenly distributed. About two-thirds of U.S. data centers built since 2022 sit in regions already facing water stress, which means the water cost of storage growth compounds fastest in the places least able to absorb it. Source: IEEE Spectrum, citing Bloomberg News, https://spectrum.ieee.org/ai-water-usage.
Most enterprise IT organizations don’t have visibility into how much of the capacity they’re cooling is actually active. A file share can carry years of cold, rarely accessed data, and every gigabyte of it still occupies primary storage, still draws power, and still generates heat that a facility’s cooling system has to remove, regardless of whether anyone has opened those files in years.
Where storage tiering fits in
Komprise doesn’t control a data center’s cooling infrastructure, and WUE improvement primarily comes from cooling system design, water reuse, and facility siting. What Komprise does control is how much of an enterprise’s storage estate has to stay active in the first place, and that’s a real, if modest, lever on the same problem.
The Komprise Global Metadatabase identifies which files across every NAS and cloud system haven’t been accessed in months or years. Transparent Move Technology then tiers that cold data off primary storage to lower-cost tiers, without rehydration and without disrupting user access. Fewer active files on primary storage means less capacity that has to stay spinning, powered and cooled. Komprise Reports quantify exactly how much data has moved and how much capacity that freed up, giving IT a concrete number to connect storage decisions to facility-level sustainability goals, alongside the cost savings tiering already delivers.
| Evaluation Criteria | Without Storage Awareness | With Komprise |
|---|---|---|
| Active footprint visibility | No way to tell how much provisioned storage is actively cooled versus sitting cold | The Global Metadatabase identifies cold, inactive data across every NAS and cloud system |
| Capacity planning | Cooling and power sized for total provisioned capacity, active or not | Data age and access metrics inform right-sizing decisions before a storage refresh |
| Storage growth trajectory | New capacity added to keep pace with unstructured data growth, cold data included | Cold data tiered off primary storage with Transparent Move Technology, reducing the active footprint that adds to cooling load |
| Cross-silo view | Cooling and sustainability data siloed per storage vendor or facility | One consolidated view of storage, growth and data age across every site and cloud |
| Sustainability reporting | No connection between storage decisions and facility sustainability metrics | Komprise Reports quantify how much data has moved off primary storage, supporting sustainability and cost reporting together |
WUE Frequently Asked Questions
What is Water Usage Effectiveness (WUE)?
WUE is a data center sustainability metric that measures water consumption per kilowatt-hour of IT equipment energy use. It was developed by The Green Grid to give data center operators a standard way to track and compare water efficiency.
How does WUE relate to Power Usage Effectiveness (PUE)?
WUE and PUE measure different resources using the same logic: PUE tracks total facility energy use against IT equipment energy use, while WUE tracks water use against that same IT equipment energy baseline. Facilities that rely on water-intensive evaporative cooling often achieve strong PUE at the cost of higher WUE, since water-cooled systems are typically more energy efficient than air-cooled alternatives.
Why does unstructured data growth affect a data center’s WUE?
More unstructured data means more storage capacity, and more storage capacity means more hardware that has to stay powered and cooled. Since most enterprise cooling systems use water, storage growth translates into rising water demand, even when a large share of that stored data is inactive and provides no business value in return for the resources it consumes.
Can storage tiering reduce a data center’s water usage?
Tiering reduces the active storage footprint that requires cooling by moving cold, rarely accessed data off primary storage, which is a contributing factor to a facility’s cooling load. It does not replace cooling system upgrades or water reuse programs as the primary levers for improving WUE, but it addresses a driver of storage growth that most sustainability initiatives don’t directly touch.
How does Komprise support data center sustainability goals?
Komprise identifies cold, inactive data across every NAS and cloud system through the Global Metadatabase, then tiers it off primary storage with Transparent Move Technology. Komprise Reports quantify the resulting reduction in active storage footprint, giving IT a way to connect data management decisions to sustainability reporting alongside the cost savings tiering already provides.