PART 17
Jay Hundley, who farms 10,000 acres in eastern Virginia, stopped irrigating his fields from Farmers Hall Creek because its low water level is allowing saltwater to intrude from Chesapeake Bay. The creek’s salt level is 3,200 parts per million, exceeding the allowable 2,200 parts per million. Instead, he irrigates from a pond using the center pivot pictured above. Photo by Doug Stroud.
In a year when every region of Virginia faces drought conditions, hundreds of data centers are withdrawing about 6 million gallons of water every day from the state’s waterways and reservoirs.
Collectively, data centers use over 2 billion gallons of water a year in Virginia.
In 2025, Amazon used 263 million gallons in the state. Just in Ashburn, Microsoft used 63 million gallons. Google used 360 million in Bristow and 378 million in Leesburg data centers, according to the companies’ reports.
On the hottest days, that can increase significantly. Data centers in Prince William County can use 10% of the water supply at peak demand — more than 4.6 million gallons in a single day, according to Prince William Water, the water authority.
Water use has emerged as a new front in the battle over data center development. Critics complain that tech companies and developers have entered into secret agreements with municipalities and water authorities to divert massive amounts of water to data centers.
Data center companies point out that industry water use adds up to less than 1% of all demand. They note that many data centers use less water than an average office building.
Fauquier County, which mostly relies on public wells, tries to shield its water supply. The county, which so far has only a handful of data centers, requires them to use closed-loop systems, which recirculate cooling water. The trade-off is that those systems use significantly more electricity than others.
Prince William Water says its robust data center development is not a threat to the water supply. Data centers use 4% of Prince William’s water, a figure expected to double by 2050.
That is manageable, said Don Pannell, the water authority’s chief operations officer. “Honestly, an increase in demand from 4% to 9% is not a dominant piece of our inventory and not a radical change,” he said.
With drought and population growth affecting water levels in the Rappahannock River, Jay Hundley worries about a data center planned upriver from his Cloverhill Farm. Photo by Doug Stroud.
Extreme heat
Data centers need water because they get hot, really hot. The huge hyperscale campuses — which house tens of thousands of computers — can create as much heat as 180,000 homes, according to a study published by the American Society of Mechanical Engineers. When a failed cooling system allows temperatures inside a data center to rise past 100 degrees, computer equipment worth billions can be fried in less than 20 minutes.
Moreover, water is needed to generate electricity, so as data centers multiply, so does indirect water use. Power plants use almost 50 trillion gallons to generate electricity, according to the Energy Information Administration. Most is returned to the water table, but 3.5% — more than a trillion gallons — is lost every year.
Like many issues surrounding data centers, information about water use can be hard to uncover because of nondisclosure agreements that developers persuade local officials to sign, said Elena Schlossberg, executive director of the Coalition to Protect Prince William County.
“We have very little information about how much water each data center campus is using,” said Schlossberg.
The county already hosts 57 data centers and 77 more are under construction or planned. In June through August 2025 — the hottest months of the year — data centers used a collective average of almost 2 million gallons a day, said Prince William Water.
Water use has been so controversial that the data center industry has invested heavily in curtailing its consumption.
“The industry has made great strides in recent years to reduce the amount of potable water used in its facilities through technical advancements, use of reclaimed water, and other innovations,” Nicole Riley, director of Virginia government affairs for the Data Center Coalition, told the Piedmont Journalism Foundation.
CloudHQ’s campus in Manassas is allowed to use 2 million gallons a day during peak demand, according to data from Prince William Water.
But in a statement, CloudHQ said the amount of water data centers actually use is less than the allowed usage: “These buildings will use highly efficient heat rejection systems and, even on the most use-intensive days, the campus will use significantly less than 2 million gallons per day. Most days, there will be no water used for cooling.”
The Stack Infrastructure campus on Hornbaker Road could use close to 300,000 gallons on a hot day, while the Manassas Tech Center on Mike Garcia Drive can use 270,000, according to data provided by Prince Wiliam Water.
Amazon says technology has allowed it to reduce its water use in Northern Virginia by 42%. However, that claim is being challenged in court by a former employee who argues that the company’s internal data contradicts its public assertions.
Even with new technologies in place, data center water use continues to climb in Prince William and elsewhere.
Across the globe, Amazon reported that its data centers used 2.5 billion gallons in 2025, while Microsoft reported 3.5 billion gallons. Google used 5 billion.
Jay Hundley and his wife, Faye, state chair of the Virginia Farm Bureau’s Women’s Committee. Photo by Doug Stroud.
Most endangered river
Prince William Water buys its water from Fairfax Water, which takes its water from the Potomac River and the Occoquan Reservoir. In addition, Prince William buys a small amount from the City of Manassas, which gets its water from Lake Manassas.
The cumulative impact has some water managers and conservationists concerned about future supplies — not just because of the amounts being used, but also because of discharged pollutants.
In April, the Potomac was named the most endangered river in the United States by the conservation group American Rivers, which cited “the rapid, unchecked buildout of data centers along the Potomac River.” The report also warned of potential contamination from data center effluent.
The Interstate Commission on the Potomac River Basin, established by Congress, had reached a similar conclusion in March, citing the 1,200 data centers slated for the Potomac’s watershed.
While the Interstate Commission and other groups say the current impact from data centers is modest, they also note the river is already battling the impact of climate change and population growth.
The U.S. Geological Survey, which monitors every major waterway in the nation, reports that the Potomac, Rappahannock and James rivers have all been designated as “extremely below” normal levels this year. Virginia, like much of the South, is in a “moderate drought” with some areas in “severe drought,” according to the U.S. Drought Monitor.
Dozens of data centers are also planned for the Rappahannock River basin. Said Brent Hunsinger, advocacy and coastal programs director for Friends of the Rappahannock: “We're concerned about the data center development from the water use perspective, but also water quality and the clearing of land and forest cover and loss of wetland.”
Salt becomes a worry
Jay Hundley farms 10,000 acres across eastern Virginia, including in Essex, King George and Caroline counties. He depends on a steady flow of fresh water coming down the Rappahannock to keep the salty tides of the Chesapeake Bay out of his irrigation system.
Salt levels are so important that he keeps meters in the Rappahannock to monitor salinity.
“I’ve never seen it this high,” he said. With his land already on the bubble due to climate change and population growth, Hundley is closely watching plans to build data centers upriver.
“If they keep building these data centers and keep taking water off these rivers, it’s definitely going to change the salt levels,” said Hundley. If it gets too salty, he said, he will have no choice but to abandon his fields.
Caroline County recently approved a proposal to withdraw 9 million gallons a day from the Rappahannock River but reversed itself after public backlash. In Louisa County, another area targeted for development, data centers are allowed to use only reclaimed water.
Still, Hunsinger and others are concerned about chemicals that data centers discharge — some of which will be returned to the Rappahannock after being treated at wastewater facilities.
A recent Department of Environmental Quality report found that the state's groundwater aquifers cannot support substantial data center withdrawals — meaning they must depend on surface sources, including reservoirs and rivers.
The details are secret
The Interstate Commission report said unrestrained data center growth, combined with population growth and global warming, could threaten drinking water supplies by 2050.
But government authorities and conservationists can only guess at data centers’ impact on water supply: No regulations require data centers to disclose water use, and data centers regularly use nondisclosure agreements to block government officials from making those figures public.
Unlike Loudoun County, Prince William has no reclaimed water facilities — nonpotable water typically used for industrial cooling — so every data center depends on potable water instead.
After cooling, the data centers release water back into the system where it is treated before ending up in the Occoquan Reservoir.
