100 MW data center water use: direct answer
For the transparent screening assumptions used here, a data center with 100 MW average IT load and PUE 1.15 requires about 1.71 million m³/year of external site water with full wet evaporative heat rejection. A hybrid case with a 35% equivalent wet share uses about 0.60 million m³/year. A closed direct-to-chip loop paired with fully dry heat rejection has no routine evaporative cooling-water demand in this model and retains only 1,825 m³/year of assumed ancillary site water. The 1.71-million-m³ result is an illustrative all-year wet case—not a fleet average or a prediction for a named project.
On a per-MW basis, those illustrative cases are about 47.0 m³/day/MW IT, 16.5 m³/day/MW IT and 0.05 m³/day/MW IT, respectively. At the same 100 MW load, changing only the assumed latent heat share from 80% to 90% moves the full-wet external-water result from approximately 1.61 to 1.82 million m³/year. These are scenario outputs, not universal industry averages; climate, PUE, operating mode, water chemistry and reporting boundary can change the result materially.
Scale the same comparison
25–1,000 MW average ITCooling-related water scales approximately with heat load in this screening model; the illustrative 5 m³/day ancillary allowance remains fixed. Real facilities also vary with weather and operating mode.
Core result
same IT load, two heat sinksAnnual external site water for full wet rejection versus a closed direct-to-chip loop with dry heat rejection. The low-water case still includes 5 m³/day of other site water.
Five cooling scenarios
same average IT load| Scenario | PUE | Wet heat share | Site WUE | Water input | Daily / MW IT | Annual input | Annual consumed |
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“Wet heat share” is an equivalent modeled share. A 35% hybrid value can represent a system that runs dry for much of the year and uses evaporation during hotter periods; it is not a universal annual operating fraction.
Annual water comparison
external site inputWhat the comparison shows
three engineering takeaways
Published WUE reference: AWS 2025
not one facilityAWS reports a 2025 global data-center WUE of 0.12 L/kWh, explicitly describing this fleet metric as water withdrawn per kWh of IT load. Applied mechanically to the same average IT energy, that corresponds to:
Why the numbers diverge
energy–water architectureMethod and assumptions
calculation details and boundaries
Baseline calculation method
Each scenario is run through the same shared engine as the Data Center Water Usage & WUE Calculator. The engine calculates total facility power from IT load × PUE, assigns a fraction of heat to the wet path, then calculates circulation, evaporation, drift, blowdown, treatment reject, site water input, consumption and WUE.
The case study uses 100% utilization because the headline quantity is defined as 100 MW average IT load, not 100 MW nameplate capacity.
Illustrative scenario assumptions
- Full wet rejection: PUE 1.15; 100% equivalent wet share; 10°C circulating-water range.
- Closed direct-to-chip + wet tower: PUE 1.15; 100% equivalent wet share; 12°C circulating-water range.
- Hybrid / seasonal wet assist: PUE 1.15; 35% equivalent annual wet share.
- Mostly dry + evaporative assist: PUE 1.15; 10% equivalent annual wet share.
- Closed direct-to-chip + dry heat rejection: PUE 1.15; 0% wet share.
- Wet cases: central latent heat share 85% (80–90% sensitivity shown above), latent heat of vaporization 2.40 MJ/kg, cycles of concentration 4, drift 0.005%, and 100% tower-makeup pretreatment recovery.
- All cases: 5 m³/day other site water, 50% assumed consumptive.
These are transparent comparison assumptions, not claims about typical or best-practice PUE/WUE values. Holding PUE at 1.15 isolates the effect of heat-rejection architecture; it does not imply that wet towers, hybrid coolers, dry coolers and chillers have identical energy performance. The model conservatively treats facility electricity as eventual site heat. Detailed design should locate electrical losses, fan and pump heat, and any useful heat export explicitly.
Why an annualized wet share is useful
Hybrid and evaporative-assist systems may operate dry during favorable weather and use water only during hotter conditions. A single steady design point cannot represent that annual behavior. The equivalent wet-share parameter lets a first-pass annual water estimate be made, while clearly signaling that an hourly weather model would be needed for site-specific design.
Site water vs electricity-related water
This case study focuses on site water. Electricity generation can have its own water withdrawal/consumption footprint, depending on the grid mix and generation technology. That upstream quantity is intentionally kept separate because adding a generic grid-water intensity can be more misleading than useful for a site-specific project.
Current technical context
why this topic is changing quickly
Related EngineerHub resources
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