Article Text
A major expansion of water-cooled data centers could nearly double current consumptive water use in the Potomac River basin, Fairfax County’s Environmental Quality Advisory Council warned in its 2024 annual report.
The 134-page report examines environmental conditions and policies involving land use, air and water quality, transportation, waste management, climate change and ecological conservation. Among its most pressing concerns is how data centers could strain the region’s water supply and wastewater infrastructure.
Data centers consume substantial amounts of electricity and generate significant heat. Some facilities manage that heat with evaporative cooling systems, which use water to cool the air.
Under one scenario outlined by the council, widespread adoption of evaporative cooling at large new data centers could consume 70 million gallons of water per day. That would “almost double” existing consumptive water use across the Potomac basin.
Regional agencies would have to secure the additional water and treat the portion eventually discharged into wastewater systems.
Evaporative cooling also produces a highly concentrated saline residue known as blowdown. Sodium levels are already a concern in the 590-square-mile Occoquan River watershed, though the issue is less pronounced in the Potomac basin, according to the report.
The council recommended that the Fairfax County Board of Supervisors consider three measures: allowing water service for data center operations to be curtailed during droughts, encouraging the use of recycled wastewater instead of fresh water for cooling, and prohibiting saline wastewater discharges in areas served by the Occoquan Reservoir.
PFAS rules could bring steep costs
The report also urged county officials to prepare for tighter Environmental Protection Agency limits on PFAS in drinking water.
PFAS, short for per- and polyfluoroalkyl substances, are synthetic chemicals that have been used since the 1940s. Because they do not naturally break down, they can accumulate over time in water, soil, food and the human body.
Meeting the EPA’s new limits could require Fairfax Water to make upgrades costing nearly $500 million by 2029. Fairfax Water acknowledged when the standards were announced last April that decades of industrial and consumer use have left PFAS throughout the environment.
Unless federal or state funding helps cover the upgrades—or the regulations are relaxed—Fairfax Water customers are expected to bear the expense.
The council did not propose a specific PFAS strategy. It recommended, however, that Fairfax Water set customer rates high enough to pay for the purchase, installation and maintenance of equipment needed to comply by the federal deadline.
A public hearing on the annual report is scheduled for Wednesday, Jan. 8, at 7:15 p.m. at the Fairfax County Government Center. Participants may comment in person, virtually during the hearing or through a recorded video. Written testimony will also be accepted through Jan. 8.