The chemical treatment employed by the Washington Aqueduct to address lead leaching in lead service line pipes and fixtures has been modified from zinc orthophosphate to orthophosphate. The change comes as a result of concerns from Arlington County that zinc orthophosphate may impact its wastewater treatment plant.

The Washington Aqueduct, which is responsible for treating the District’s water, also supplies water to Arlington County and Falls Church. The start date for the Washington Aqueduct to begin adding the chemical treatment to the water that is distributed to a small area in the Northwest quadrant of the city remains the same, on or about June 1.

Both chemicals work as corrosion inhibitors that form a protective coating inside of lead service line pipes and fixtures to prevent lead from leaching into drinking water.

A public meeting will be held Wednesday, June 2, 6:30 to 8:00 pm at the Blessed Sacrament Shrine Church, 5841 Chevy Chase Parkway to answer residents’ questions about the addition of orthophosphate.