The water main break in Arlington has impacted parts of upper NW DC. Some areas areas are under a boil water alert. Here is an interactive map showing which areas are affected:
https://www.arcgis.com/home/webmap/viewer.html?webmap=2ab86ced18ab41a3b7c3d0517b5bff16&extent=-77.1629,38.8733,-76.9093,38.9963