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Arlington County will temporarily change its water disinfectant and flush hundreds of miles of pipes this spring as part of annual maintenance across the region.

From March 23 through May 4, 2026, most of Arlington’s water system will switch from chloramine, the disinfectant used throughout the year, to chlorine. In the Willston Pressure Zone, which is served by Fairfax Water, the change will remain in effect through May 26.

Water service will continue without interruption, and the water will remain safe to drink. Some customers may notice a stronger chlorine taste or odor during the work.

County employees will monitor chlorine levels throughout the process to ensure the water continues meeting federal and state requirements.

The temporary change will also occur in the District of Columbia and northeastern Fairfax County. The Washington Aqueduct, operated by the U.S. Army Corps of Engineers, supplies water to Arlington and neighboring jurisdictions and initiates the annual disinfectant change as a standard treatment practice.

Arlington’s water is not affected by the recent DC Water sewage spill in the Potomac River. The main intake for the Dalecarlia Water Treatment Plant, near Great Falls, is upstream from the spill.

Along with changing disinfectants, Arlington will flush the entire distribution system to clear water mains and support water quality. Residents may see fire hydrants running during the work.

Hydrant flushing is scheduled from 9 a.m. to 3 p.m. on weekdays. The process can stir up sediment and temporarily discolor nearby tap water, potentially staining clothes in the wash. Residents may want to avoid doing laundry while flushing is underway in their area.

Anyone whose clothing is stained by the work may request a special detergent from the county by calling 703-228-5000.

Residents can reduce chlorine taste or odor by using a tap filter or leaving water in an open container in the refrigerator for one or two hours. Customers who normally take special steps to remove chloramine should continue following their treatment practices during the switch to chlorine. People with health-related concerns should consult their health care provider.

Arlington’s water network includes about 500 miles of pipes serving homes, businesses and schools. County drinking water continues to meet or surpass safety standards established by the Environmental Protection Agency and the Virginia Department of Health.

Questions may be directed to 703-228-5000 from 7 a.m. to 7 p.m. Monday through Friday. Arlington also operates a 24-hour line at 703-228-6555.