A massive heatwave sweeping across the United States is straining the country’s power grid and water supplies, testing public support for the rapid expansion of AI data centres, which consume vast amounts of electricity and water.

The heatwave comes at a time when the US is racing to build thousands of new AI data centres to support the rapid growth of artificial intelligence. Utilities, regulators, and policymakers have increasingly warned that the pace of construction is outstripping the expansion of the country’s electricity and water infrastructure.

Across the political spectrum, lawmakers are calling for increased oversight of data centres. Texas Governor Greg Abbott called for a ban on building data centres in rural areas during a campaign stop on Tuesday. The sitting Texas governor has previously said that data centres should generate their own power and reuse water.

Meanwhile, on the left, politicians, including Senator Bernie Sanders of Vermont and Representative Alexandria Ocasio-Cortez of New York, called for a moratorium on the construction of new data centres.

Pushing back on data centre construction is a popular position to have. Seven in 10 Americans opposed data centre construction in their local communities, according to a recent Gallup survey, with half of them citing the excessive use of resources, including power and water supply, as a main concern.

Data centres account for 4 percent of US power demand. That is expected to increase to 9 percent by 2030, according to the US Department of Energy.

The heat dome blanketing much of the US is a test of the nation’s power system that is increasingly being pressured by extreme weather events.

“Heatwaves are demonstrating that the current siting and cooling model was designed for average conditions, and average conditions are disappearing with each passing day,” Arif Gasilov, partner leading natural resources & built environment practice at Gasilov Group, told Al Jazeera.

Power providers see this.

On the US east coast, PJM Interconnection, the nation’s largest power grid operator, asked the US Department of Energy to order data centres to switch to backup power generators within 15 minutes of an emergency signal alerting them to do so. PJM, which operates power grids in 13 states and the nation’s capital, said that would free up power for residential and commercial customers.

The power provider requested the change as a so-called heat dome locks in across the Eastern Seaboard, with feel-like temperatures expected to exceed 38.9 Celsius (104 Fahrenheit) in Washington, DC and  37.7 Celsius (100 Fahrenheit) in New York. In Central Park, the temperature is expected to hit a record high not seen in the iconic park in more than a decade.

In the US, the majority of the data centres are located in the South and Midwest, and 38 percent of Americans live within five miles (eight kilometres) of one of the 3,000 currently operational data centres, according to data compiled by Pew Research.

During normal temperatures, data centres’ cooling systems alone account for as much as 40 percent of electricity usage during normal weather, but that increases as the temperature elevates, an increasingly common occurrence now because of climate change, according to Gasilov.

Data centres are already driving up temperatures around the globe by creating what are called heat islands around them. A University of Cambridge study found that temperatures increased by an average of two degrees Celsius (3.6 degrees Fahrenheit), and by as much as 9.2 degrees Celsius (16.3 degrees Fahrenheit) in the immediate vicinity of a data centre.

Experts believe that this heatwave is an example of the pressures on the power grid that will become even tighter and harder to manage in the years to come as the prevalence of water- and power-intensive AI data centres surges.

The strain extends well beyond this heat dome.

Utilities across the country have warned that electricity demand is growing for the first time in decades after years of relatively flat consumption. Much of that increase is being driven by AI data centres, the electrification of transportation, and new manufacturing facilities, forcing utilities to delay the retirement of ageing power plants while accelerating investment in new generation and transmission lines.

This pressure has already been mounting on both commercial and residential customers around the US. Earlier this year, roughly 50,000 California customers near Lake Tahoe were told to find a new power provider amid increased data centre-driven demand.

In Virginia, Henrico County, which has 37 data centres, asked schools to limit power usage amid growing demand on the power grid, according to emails obtained by the tech publication 404 Media.

Virginia overall leads the country in the sheer number of data centres, with 398 currently operational and another 287 planned. That is followed by Texas, with 296 open and another 170 planned.

A typical hyperscale data centre requires between 100 and 300 megawatts of electricity. That is enough to power as many as 300,000 US homes, or a city of roughly 750,000 people based on the average household size. That is comparable to the populations of cities like Nashville in Tennessee, Charlotte in North Carolina or Edmonton in Alberta, Canada.

Taken together, US data centres consume about 176 terawatt-hours of electricity each year, enough to power roughly 16 million homes, or power for about 40 million people, roughly equivalent to the population of Canada or California, or the cities of Jakarta in Indonesia or Dhaka in Bangladesh, which are the world’s two most populous cities.

This is also putting pressure on water systems, many of which are already strained.

Water pressure

Water demand at data centres increases during periods of extreme heat because cooling systems have to keep computer servers cool so they can operate safely. Many of the systems do not recirculate water. Nearly 80 percent of the potable drinking water used in data centre cooling evaporates.

“If a facility uses evaporative cooling during a heatwave, it is using the same water supply that’s already stressed and that residents are often already under restrictions for,” Gasilov added.

Currently, data centre water usage is comparatively low at 627 million gallons (2.85 billion litres) per day compared with usages like cattle at 137 billion gallons (623 billion litres), the steel industry at 1.8 billion (8.2 billion litres) and residential usage at 23.3 billion gallons (104.5 billion litres).

As demand for AI continues to surge, so, too, will the industry’s water consumption. The issue is compounded by the fact that data centre expansion is increasingly concentrated in water-stressed areas: two-thirds of all new data centres built or in development since 2022 have been located in regions already facing water scarcity.

A single large AI data centre can consume as much as 5 million gallons (18.9 million litres) of water each day. That demand typically rises during the hottest periods of the year — precisely when many communities are also facing water shortages.

“A lot of cooling at data centres rely on water – and again – this will come at a time when the supply may well be at its scarcest in the local environment. This is a circular problem in this space, not a seasonal inconvenience,” Alex MacColl, project manager for EMEA for Datamove, a data centre mitigation service based in the UK, told Al Jazeera.

A large data centre specifically can also use as much water as a city of 50,000 people each day, according to the Environmental and Energy Institute, and that is roughly 15 percent of the entire population of Corpus Christi, Texas, where local and state officials are already concerned the city could soon run out of fresh drinking water. There are currently three data centres in the greater Corpus Christi area, although one asserts it uses “zero water”.

Some of its reservoirs are below 10 percent capacity as the area has been in a drought for the past five years. According to reporting from the Austin American-Statesman, local officials believe that a planned data centre in a community an hour north has slowed plans for an emergency water supply for the coastal Texas city.