Link: https://www.theregister.com/2026/03/10/us_datacenters_water_consumption/

Public water supplies in America will need billions invested to meet the peak requirements of datacenters during the hottest periods of the year, even if their overall annual consumption is relatively modest.

A study by researchers at the University of California, Riverside, acknowledges that water is an efficient means of cooling for server farms, which are looking to minimize their power usage.

But it warns that the growing water demand will lead to substantial peak withdrawals, which many communities in the US do not have the capacity to supply, particularly during the hottest days of the year.

Without new water efficiencies, datacenters across America may require 697 million to 1.45 billion gallons of extra peak water capacity per day by 2030, the study estimates. This compares with New York City's daily water supply of about a billion gallons.

Not like we have any other uses for water in a rapidly heating world.

New York City is a port city. It has an effectively infinite supply of salt water, which you can use for evaporative cooling, albeit with some extra complications.

EDIT: Hell, you can use the waste energy from an evaporative cooler to drive a distiller to generate fresh water from some of the evaporated salt water, if you want. Microsoft is doing that combined datacenter-nuclear-power-plant thing. IIRC, if I'm not combining two different cases of an AI datacenter using full output of a power plant, they have the entire output of a nuclear power plant never touching the grid (and thus avoiding any transmission cost overhead and as a bonus, avoiding regulatory requirements attached to transmission and distribution from power generation):

https://arstechnica.com/ai/2024/09/re-opened-three-mile-island-will-power-ai-data-centers-under-new-deal/

Re-opened Three Mile Island will power AI data centers under new deal

Microsoft would claim all of the nuclear plant’s power generation for at least 20 years.

From past reading, desalination from reverse osmosis has wound up being somewhat cheaper than via using distillation, but combined generation-distillation using waste heat is a thing. IIRC Spain has some company that does combined generation-distillation facilities.

And in a case like that, you have the waste heat from generation and the waste heat from use all in one spot, so you've got a lot of water vapor to condense.

EDIT2: Yeah, apparently distillation used to be ahead for desalination, but reverse osmosis processes improved, and currently hold the lead:

https://www.sciencedirect.com/science/article/pii/S1359431124026292

As desalination is a process of removing dissolved solids such as salts and minerals from water, there are two main types of technology commonly used in the industry: thermal-based and membrane-based [22]. The thermal-based desalination processes, such as multi-stage flash distillation (MSF) and multiple-effect distillation (MED) were once predominantly used in the water sector until membrane-based desalination technology, such as reverse osmosis (RO), matured and offered lower operating costs [23]. Hence, RO is the most used desalination process today, producing between 61 % and 69 % of the total global desalinated water, followed by MSF (between 17 % and 26 %) and MED (between 7 % and 8 %) [9], [16], [19], [20], [24].

They could also use treated waste water for cooling the data centers instead of dumping it in the ocean.

Yeah, there's some nuclear power plant here in the US that uses sewage for cooling. It's out in the middle of the desert, Arizona or New Mexico or something, somewhere where it'd be a pain to bring in a bunch more water.

searches

Arizona.

https://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_Station

The Palo Verde Generating Station is a nuclear power plant located near Tonopah, Arizona[5] about 45 miles (72 km) west of downtown Phoenix. Palo Verde generates the second most electricity of any power plant in the United States per year, and is the second largest power plant by net generation as of 2021.[6] Palo Verde has the third-highest rated capacity of any U.S power plant. It is a critical asset to the Southwest, generating approximately 32 million megawatt-hours annually.

At its location in the Arizona desert, Palo Verde is the only nuclear generating facility in the world that is not located adjacent to a large body of above-ground water. The facility evaporates water from the treated sewage of several nearby municipalities to meet its cooling needs. Up to 26 billion US gallons (~100,000,000 m³) of treated water are evaporated each year.[12][13] This water represents about 25% of the annual overdraft of the Arizona Department of Water Resources Phoenix Active Management Area.[14] At the nuclear plant site, the wastewater is further treated and stored in an 85-acre (34 ha) reservoir and a 45-acre (18 ha) reservoir for use in the plant's wet cooling towers.