Ashburn's
Hidden Bill

Not a single day has passed without data centre construction in Loudoun County, Virginia in fourteen years. The statistic, confirmed by county officials in their own planning documents, barely registers the strangeness of what has happened to a stretch of land between the Dulles Toll Road and the Blue Ridge foothills. Once known for horse farms, Civil War battlefields, and commuter sprawl, the unincorporated community of Ashburn has quietly become the most important piece of technology infrastructure on earth.

Roughly 70 percent of the world's internet traffic passes through this corridor at some point. Not some of it — most of it. Emails, cloud storage, streaming, financial transactions, the query you typed into a search engine this morning. Somewhere in what the industry calls "Data Center Alley," a server rack processed it. The concentration is so extreme that Northern Virginia holds approximately 13 percent of all reported data centre operational capacity in the entire world, and fully 25 percent of the capacity used in the Americas, according to analysis by the Virginia Joint Legislative Audit and Review Commission (JLARC) using data from Cushman & Wakefield's 2024 Global Data Center Market Comparison. It outpaces the second-largest market, Beijing, by more than two to one.

This did not happen by accident, and it did not happen for free. Northern Virginia's dominance was built on a convergence of specific advantages — proximity to government fibre infrastructure built in the Cold War, access to the Potomac River's relatively abundant water supply, and, critically, an aggressive suite of tax incentives that have made Virginia one of the cheapest places on earth to build and operate a data centre. Since 2010, Virginia has exempted data centres from the state's sales and use tax on equipment. The cumulative value of that exemption now exceeds $2.7 billion. In fiscal year 2025 alone, it was worth $1.9 billion — equivalent to two percent of the state's entire budget, and 80 percent of all economic incentive spending.

The electricity numbers are where Loudoun County's situation becomes something that no longer fits within the ordinary frame of economic development. In 2018, when data centres first broke the 1 gigawatt threshold of consumption in the county, the figure was considered remarkable. By 2025, consumption had reached 5.33 gigawatts — a 176 percent increase in seven years. Independent analyses by Loudoun County and engineering firm Kimley-Horn, conducted separately and arriving at nearly identical conclusions, project the county will require 11 to 12 gigawatts by 2028 or 2029. That is roughly the output of twelve large nuclear reactors, dedicated to a single county in northern Virginia.

The state's official energy utility, Dominion Energy, has not sugarcoated the challenge. At a July 2024 public meeting, Dominion officials confirmed that data centre electricity consumption in Virginia had surged 231 percent in just eight years. The company has committed to investing $50.1 billion in capital projects — transmission lines, substations, and generation — between 2025 and 2029, a construction programme of a scale rarely seen outside wartime mobilisation. The question that nobody in Richmond has satisfactorily answered is who pays for it.

The answer, emerging slowly through regulatory proceedings and academic research, is: largely everyone else. Data centres currently account for 24 percent of Dominion Energy's electricity sales in Virginia. The Virginia State Corporation Commission found that PJM's capacity auction in 2024 saw an 833 percent price increase for the 2025–2026 delivery year, driven overwhelmingly by AI data centre demand in Northern Virginia. That cost propagates outward through every electricity bill in the mid-Atlantic region. Residential customers in western Maryland are paying approximately $18 more per month. JLARC's December 2024 analysis projected that Dominion residential bills could increase by $444 per year by 2040 if data centre growth continues unconstrained. Data centres receive the electricity; ordinary households absorb a portion of the infrastructure cost required to deliver it.

The energy story has, at least, attracted legislative attention. The water story has not. It is newer, its data is harder to obtain, and it arrives at a moment when Northern Virginia's rivers and reservoirs are not yet in crisis. But the trajectory is clear enough that researchers who spend their careers thinking about long-term water supply are beginning to use language that does not usually appear in technical reports.

Data centres use large volumes of water to cool their servers — either drawing directly from municipal supplies or from surface water sources, running it through evaporative cooling systems, and losing much of it to the atmosphere. The water does not come back. Alimatou Seck, a senior water resources scientist at the Interstate Commission on the Potomac River Basin, worked with local water utilities to calculate how much. Working from figures that data centre operators are not required to disclose publicly, she found that the facilities in "Data Center Alley" currently consume approximately 2 percent of the water drawn from the Potomac River Basin. During the summer months — when temperatures rise, cooling demands increase, and river flows typically fall — that figure reaches 8 percent.

Seck then projected forward, using standard data centre growth rates and conventional cooling technologies. Her estimate: if growth continues on its current trajectory, data centres could claim more than 33 percent of the Potomac River Basin's water by 2050, requiring 200 million gallons per day. The Potomac, it should be remembered, is also the primary source of drinking water for Washington D.C. and its surrounding communities — including the same Loudoun County residents who live beside the data centres.

The figure that should animate policymakers is not 2 percent. It is not even 8 percent. It is the speed of the trajectory. A Freedom of Information Act request filed by the Piedmont Environmental Council found that data centres served by Loudoun Water — the county's water authority — increased their consumption of drinking water by more than 250 percent between 2019 and 2023. Four years. A 250 percent increase in drinking water consumption, in the same watershed that supplies the capital of the United States.

University of California Riverside engineering professor Shaolei Ren, whose research has focused specifically on the water costs of AI computation, estimates that a 100-word AI prompt consumes approximately 519 millilitres of water — roughly one standard water bottle. His team's projections suggest that the water demands of AI globally could grow to consume half the United Kingdom's annual water use by 2027. That demand is not evenly distributed across the planet. A disproportionate share of it concentrates in the watersheds where data centres are densest. In Northern Virginia, that means the Potomac.

There is a standard argument made by the data centre industry and its supporters in Richmond: the facilities bring tax revenue, support jobs, and attract further investment. The argument is not wrong, exactly. Loudoun County's data centres pay approximately $666 million per year in Business Personal Property Tax. The industry supports — directly and indirectly — an estimated 74,000 jobs and $9.1 billion in annual Virginia GDP. These are real numbers, and the communities that have benefited from them are real communities.

But the accounting is incomplete in ways that matter. A 250,000-square-foot data centre — a facility that could occupy a significant portion of a residential neighbourhood — employs approximately 25 direct workers once construction is finished. The construction jobs are temporary; the operational jobs are few. Meanwhile, the energy infrastructure required to power that building cascades outward through the grid in costs that accrue to households who had no vote on the original planning application. And the tax exemptions that attracted the investment represent a subsidy of a scale that has quietly become the dominant fact of Virginia's economic incentive system.

Good Jobs First, a nonprofit that tracks state economic subsidies, calculates that Virginia's data centre incentive costs ballooned by 1,051 percent since the programme began. What was expected to cost approximately $1.5 million annually when the exemption was created in 2010 cost $1.9 billion in fiscal year 2025. The original projection was off by a factor of more than 1,200. The exemption now consumes 80 percent of all economic incentive spending in the state — making data centres, in effect, Virginia's only economic development priority, whether the legislature intended that or not.

On March 18, 2025, the Loudoun County Board of Supervisors voted 7–2 to end all "by right" data centre development in the county. It was a bipartisan vote — the kind that happens when a political issue has migrated from the realm of economics into the realm of lived experience. The vote did not stop existing construction. It did not rezone a single existing facility. It grandfathered 22 data centres already in the pipeline. But it marked a specific moment: the county that coined the phrase "Data Center Capital of the World" had decided, for now, to stop adding to the title.

The drivers were multiple and mutually reinforcing. Energy infrastructure in the county was constrained to the point where Dominion's own engineers said it was approaching the physical limits of what the existing grid could absorb. Water consumption was accelerating without adequate public disclosure. Air quality was deteriorating — Virginia has permitted approximately 9,000 backup diesel generators for data centres, each the size of a rail car, and facilities are permitted to run them for 50 hours at a time for "demand response" purposes. "No other land use that I know of uses as many generators as a data centre does," said Julie Bolthouse, director of land policy at the Piedmont Environmental Council, in a widely-cited 2024 interview.

The electricity bill question may ultimately prove the most durable political irritant. Virginia's SB253, introduced in early 2026, proposed raising data centre electricity rates by 15.8 percent while cutting residential bills by $5.52 per month — an explicit reallocation of the grid capacity costs that data centres currently share with ordinary households. The bill reflected a growing legislative consensus that the current cross-subsidisation is untenable. Data centres benefit from PJM capacity auction costs that in 2025–2026 represented 63 percent of Dominion's total power capacity bill. Those costs reach every electricity customer in the service area.

The data centre industry will not leave Northern Virginia. The fibre infrastructure, the regulatory relationships, the existing campuses, the proximity to the federal government's computing needs — these advantages are structural and durable. What is changing is the political and ecological arithmetic around the industry's continued expansion. The era in which Loudoun County welcomed every proposal, waived every tax, and absorbed every grid constraint is over. The question is whether the era that replaces it arrives with deliberate planning or as a series of compounding crises.

Alimatou Seck, the ICPRB water scientist, has made her projection: 33 percent of the Potomac River Basin by 2050, if nothing changes. The Loudoun County Board of Supervisors has made its vote. The Virginia General Assembly is, fitfully, beginning to ask which customers should pay for which infrastructure. The demand for data — for AI computation, for cloud storage, for the 70 percent of global internet traffic that passes through this corridor — is not going to slow. What is being negotiated, right now, is the question of what obligations accompany that demand, and who absorbs the costs when the answer has been "none."

The internet runs through a stretch of land in northern Virginia the size of 100,000 football fields. Not a single day has passed without construction there in fourteen years. The bills for that construction — in electricity, in water, in foregone tax revenue, in grid capacity — are beginning to come due. The county knows. The state is learning. The question is whether the reckoning happens on terms that the communities living beside these buildings had any part in setting.