Washington Aqueduct where the water treatment process starts courtesy DC Water
From DC Water:
“We saw this post earlier this morning and wanted to contribute to the information sharing. The musty odor and taste that some residents are experiencing are caused by algae byproducts that occur seasonally in the Potomac River and drinking water reservoirs. The concentrations of these byproducts are extremely low and are not harmful to human health.
This year has been particularly noticeable, but the taste and odor should disappear very soon because of the colder weather. A carbon-based filter, such as a Brita pitcher, will help to reduce the taste and odor. The Potomac River and the drinking water in the District’s distribution system are constantly monitored to ensure the safety of the water. If you have any questions about the quality of your drinking water, please contact our Drinking Water Division at 202-612-3440 (M – F, 8am – 4:30pm).