Washington Aqueduct Returns to Chloramine to Disinfect Area Tap Water

May 24, 2023

This week, the Washington Aqueduct’s water treatment plants resumed using chloramine (chlorine plus ammonia) for drinking water disinfection. The Washington Aqueduct treats and provides water to the District of Columbia and other regional municipalities.

Chloramine provides long-lasting protection as water flows through the District’s large distribution system and to the tap. Chloramine also lowers the levels of certain byproducts of water disinfection, known as disinfection byproducts (DBPs). In February, the Aqueduct temporarily switched to free chlorine instead of chloramine, which is a standard practice in the water utility industry. It is performed annually to keep water mains clean and free of potentially harmful bacteria throughout the year.

As always, the District of Columbia Water and Sewer Authority (DC Water) will monitor the drinking water regularly to ensure it meets or exceeds all drinking water standards. Customers may continue to notice a chlorine taste and odor for an additional week before the chloramine reaches the entire water distribution system. This taste may be reduced by refrigerating a pitcher of drinking water overnight.

Individuals and business owners who normally take special precautions to remove chloramine from tap water, such as dialysis centers, medical facilities, and aquatic pet owners, should make sure they continue with these precautions as the disinfectant returns to chloramine again. For more information, contact the Drinking Water Division at (202) 612-3440 www.dcwater.com/waterquality. After hours, customers may call the 24-hour Emergency Call Center at 202-612-3400.