Va. subcommittee delays mandate for data-center rainwater systems, asks agencies to craft best practices

Senator Angela Williams Graves, chair of the Senate subcommittee on agriculture, conservation and natural resources, on Tuesday continued Senate Bill 521 and asked state agencies to develop best practices for rainwater harvesting by data centers rather than impose an immediate mandate.

The bill, introduced by the patron, would require new data centers or those expanding by 10% or more to include a rainwater-harvesting system that captures at least 30% of rooftop surface area for nonpotable uses such as irrigation or cooling. Sponsor remarks said the measure aims to make data centers “more conservation minded” and to help recharge groundwater.

Supporters testified that rooftop capture is feasible and can provide a backup source for cooling. “In our home or our business it would be catastrophic. Same thing goes to data centers,” said Tyrone Jarvis, a certified rainwater-harvest designer and installer, who said his business has relied on harvested rainwater for 10 years and pointed to examples of the technology in nearby states.

Leslie Jarvis, also testifying for the bill, cited DEQ data showing a 7.7% increase in groundwater withdrawals (2024) and argued the requirement acts at the practical moment—during new construction or expansion—so groundwater demand is not locked in for decades without alternatives. “The bill does not ban groundwater use. It does not apply retroactively,” she said.

Industry witnesses urged caution. Nicole Riley of the Data Center Coalition said members are already pursuing rainwater and reclaimed-water options but that a single prescriptive mandate may not account for different business models. “A better approach would be to look at how does all of this coalesce together and how we can move forward with some more innovative ways,” Riley said.

A DEQ technical witness said the bill focuses on roof water only, that current stormwater guidance already allows rooftop harvesting, and that the Virginia Department of Health has primary authority over health regulations for reuse. DEQ staff underscored technical issues—such as how storage and evaporation can concentrate nutrients—and recommended agency participation in any work group.

After questions about downstream impacts and definitions (including whether small buildings might meet a narrow data-center definition), Chair Graves proposed reporting the bill with a recommendation for a work group or writing a letter to DEQ and VDH to develop best practices and a deadline. The committee voted to continue the bill to 2027 and request agency-developed best practices and further technical review.

The subcommittee’s action keeps SB 521 alive while directing agencies to study implementation details and the hydrologic consequences of rooftop capture before imposing a statutory mandate.