AI Data Center Water Estimates Rest on One Assumption

Water

Last updated 17 August 2026

Two figures are circulating as evidence that AI data centers are draining Western water supplies: 21,600 acre-feet and 89,700 acre-feet. Both come from a single July 2025 report by Western Resource Advocates, an environmental advocacy group, and both are conditional projections rather than measurements of any operating facility. Projection

The short version

• Western Resource Advocates projects on-site data center water use across five Western states at 13,700 acre-feet in 2030 and 21,600 acre-feet in 2035. Projection
• That estimate assumes conventional water-based cooling, applying a national average intensity of 0.36 liters per kilowatt-hour to utility load forecasts.
• About 76 percent of the larger 89,700 acre-feet figure is power plant water rather than data center cooling water. Derived
• The same report records that Central Arizona operators are using air cooling and that Southern Nevada has banned new evaporative cooling.

Where do the 21,600 and 89,700 acre-feet figures come from?

Both originate in Data Center Impacts in the West, published by Western Resource Advocates in July 2025. The group estimated on-site consumptive water use for new data centers in Arizona, Colorado, Nevada, New Mexico and Utah at 13,700 acre-feet per year in 2030 and 21,600 acre-feet per year in 2035.

Western Resource Advocates derived those figures by applying a national average on-site water intensity of 0.36 liters per kilowatt-hour, equal to 95 gallons per megawatt-hour, to energy demand projections filed by seven of the eight largest utilities in the region. The report states the condition plainly: the estimate holds only if those facilities use conventional water-based cooling technologies. Claim

What does the 89,700 acre-feet figure actually measure?

The 89,700 acre-feet figure is a power generation estimate, not a cooling estimate. Western Resource Advocates calculated it by assuming the projected data centers draw electricity from combined-cycle gas plants, which the group puts at roughly 300 gallons per megawatt-hour against 95 gallons per megawatt-hour consumed on-site.

Subtracting the on-site projection from the total leaves 68,100 acre-feet attributable to power generation, or about 76 percent of the figure (89,700 minus 21,600, divided by 89,700). Derived The report notes that data centers powered by renewables would carry lower water demands, and those drawing on existing coal plants would carry higher ones.

Is the water-cooling assumption holding where water is scarcest?

Not in the two markets under the most Colorado River pressure, according to the same report. Western Resource Advocates records that Salt River Project staff said data centers in Central Arizona have been using air-cooling technologies and that they expect new facilities to do the same. Claim The report also states that the Southern Nevada Water Authority adopted a moratorium on new evaporative cooling systems in commercial and industrial buildings, which means new data centers in the Las Vegas Valley must be air-cooled.

The trade-off is energy rather than nothing. Citing a Central Arizona case study, the report says a dry-cooled data center used approximately 13 percent more energy annually than a comparable hybrid wet and dry-cooled facility, while eliminating on-site water use. AI Race Facts has covered this displacement pattern in earlier reporting on per-query water claims.

How much does cooling choice change the number?

Cooling approach	Water intensity	As of
Hybrid wet and dry, Central Arizona case study	6.47 L/kWh	2022
National average, all data center types	0.36 L/kWh	2023
Amazon Web Services, company-reported	0.15 L/kWh	2025
Dry cooled, Central Arizona case study	0.11 L/kWh	2022

The spread between the top and bottom rows is roughly 59 times (6.47 divided by 0.11). Derived Because the projection was built on the 0.36 figure, a shift toward dry cooling pushes the result down and a shift toward hybrid wet cooling pushes it sharply up. The five states named are a utility service footprint rather than a watershed. Western Resource Advocates puts Nevada's full annual Colorado River allocation at 300,000 acre-feet, which makes the 2035 projection about 7 percent of that single allocation. Derived Related coverage sits in the AI Race Facts water section.

Disclosure. Western Resource Advocates is an environmental advocacy organization that works to decarbonize the power sector in the five states its report covers, and it published the report alongside a set of policy recommendations.

Frequently asked questions

How much water do AI data centers in the West use today?

No comprehensive figure exists. Western Resource Advocates states in its July 2025 report that decision makers lack comprehensive information on data center cooling systems and water use, and recommends mandatory reporting to close that gap. Every public figure for the Interior West is a projection built on utility load forecasts rather than a measurement of installed facilities.

Is 21,600 acre-feet a large amount of water?

It depends on the comparison. Western Resource Advocates says 21,600 acre-feet serves roughly 194,000 people for a year, and puts Nevada's full Colorado River allocation at 300,000 acre-feet per year. The 2035 projection equals about 7 percent of that single state allocation, spread across five states and ten years.

Does dry cooling solve the problem?

It moves the problem. The Central Arizona case study cited by Western Resource Advocates found a dry-cooled data center eliminated on-site water use while consuming approximately 13 percent more energy per year. Unless that electricity comes from wind or solar, the water reappears at the generating station rather than at the facility.

Sources

1. Western Resource Advocates, Data Center Impacts in the West: Policy Solutions for Water and Energy Use, July 2025.
2. The Colorado Sun, Colorado data centers: An FAQ on water use, AI and more, 26 January 2026, updated 29 January 2026.
3. Lawrence Berkeley National Laboratory, 2024 United States Data Center Energy Usage Report, December 2024. Cited by source 1 as the origin of the 0.36 L/kWh figure.
4. Karimi et al., Water-energy tradeoffs in data centers: A case study in hot-arid climates, Resources, Conservation and Recycling, June 2022. Cited by source 1 as the origin of the 6.47 and 0.11 L/kWh figures.

Last updated 17 August 2026