TL;DR · 30-second read

The Short Version

A company wants to build a data center, a large building full of computers, in Salem, Oregon. On the hottest days, its design lets it use up to 3 million gallons of water, about four and a half Olympic swimming pools, mostly to keep those computers cool.

Over a full year it expects to use far less, about 39 million gallons. The catch is timing: its thirstiest days are the same hot days when everyone else in town is also using the most water.

Salem’s city council is now discussing whether to pause projects like this.

A data center proposed for Salem, Oregon, is designed to use up to 3 million gallons of water a day on the city’s hottest days and roughly 39 million gallons over a full year, the Salem Reporter reported on August 5, 2026. The figures describe the first phase of a proposed multi-phase project from developer Verrus.

The numbers arrive as local opposition grows. Residents holding signs against the project attended a Salem City Council meeting this summer, where the council heard public comment and discussed the process for a possible moratorium on the project.

Executive Summary

The two water figures attached to Salem’s proposed data center describe very different things. Roughly 39 million gallons a year works out to an average of about 107,000 gallons a day. The design peak of 3 million gallons on the hottest days is roughly 28 times that average. The annual number describes volume; the peak number describes how much capacity the city’s water system must be able to deliver on a single day.

That distinction matters because water systems are sized, and water is rationed, around the highest-demand days of the year. A facility whose use spikes during heat waves asks for the most water precisely when residential and irrigation demand is also at its maximum and western Oregon is in its dry season.

For the wider data center industry, Salem is a preview of the question operators will increasingly face: not how much water a campus uses in a year, but how much it needs on the worst day, and who gets priority when the two collide.

The Number That Matters Is the Peak Day

An annual figure of 39 million gallons sounds modest next to a city’s total water use, and that is the figure most likely to appear in a sustainability report. But the arithmetic behind the two disclosed numbers tells a different story. Spread evenly, 39 million gallons is about 107,000 gallons a day. The 3-million-gallon design peak is roughly 28 times that. Put another way, just 13 days at full peak would consume the entire annual total. The facility’s water demand is not a steady trickle; it is a low baseline with sharp spikes tied to temperature.

Water utilities plan around those spikes. Treatment plants, pumps, pipes and storage reservoirs are built to meet the maximum-day demand, not the yearly average, because running short on one hot afternoon is the failure that matters. A large user whose demand concentrates in heat waves therefore consumes a disproportionate share of the system’s capacity, even if its annual share looks small. That is why the annual figure understates the strain, and why the peak figure is the one city engineers and councils need to evaluate.

The people most affected are the ones already competing for water on those days: households watering lawns and gardens, farms irrigating crops, and the rivers that carry less water in late summer. A data center’s peak does not create that summer squeeze, but it lands directly on top of it.

Why Cooling Demand Tracks the Thermometer

Data centers turn nearly all the electricity they use into heat, and that heat has to go somewhere. One of the most energy-efficient ways to move it out is evaporation: warm water passes through cooling towers, some of it evaporates, and the evaporation carries heat away, much as sweat cools a person. The hotter and drier the outside air, the more water that approach consumes. A design that uses little water most of the year but spikes on hot days is the typical signature of cooling that leans on evaporation when outside air alone is not enough.

The alternative, often described as closed-loop or dry cooling, recirculates the same water and rejects heat through fans and chillers, much like a car radiator. It uses far less water but more electricity, and its electricity demand also rises on hot days, when the regional power grid is under its own peak load. Neither choice is free. The design decision determines whether a facility leans on the water system or the power system during a heat wave, and on the hottest days both are stretched.

A First Phase, and a Council Weighing a Pause

The disclosed figures cover only the first phase of a multi-phase project. Whether later phases would add proportionally to peak water demand, use a different cooling design, or rely on another water source has a direct bearing on how the city should read the first-phase numbers. A peak figure that is manageable for one building could look different across a full campus.

The council’s discussion of a possible moratorium reflects how quickly the conversation shifts once peak-day figures are public. Communities elsewhere have used tools short of an outright pause: caps on peak-day withdrawals, contracts requiring a facility to curtail water use during declared shortages, requirements to use recycled rather than drinking water, and on-site storage that fills during cool periods. Which of these, if any, are on the table in Salem is not yet clear, but they show that the peak problem has engineering and contractual answers, not only yes-or-no ones.

Background

Salem is Oregon’s capital, and Oregon has long been a data center destination, with large campuses in Hillsboro west of Portland and along the Columbia River in The Dalles and in Central Oregon at Prineville. Cool climates, available land and access to power have drawn operators, and water has become a recurring point of friction: in The Dalles, the scale of Google’s water use became public only after a public-records dispute.

Across the industry, water disclosure has lagged behind energy disclosure. Operators often report annual totals or efficiency ratios in sustainability reports, but peak-day demand, the figure that determines how much capacity a municipal system must provide, is rarely published. As data center demand grows, local governments are increasingly asking for that number before approving new campuses.

Sources

Source: Data center designed to use up to 3 million gallons on Salem’s hottest days — Salem Reporter coverage of the proposed data center’s peak and annual water use.