Sewer


 * Sewer (metro), an underground link between Pennsylvania Avenue and Seward Square.
 * Dry Sewer, the basement of Our Lady of Hope Hospital with entrance from Dupont Circle.
 * Tepid Sewer, a Mole Rat infested Raider base under ground between Georgetown and the Anchorage Memorial.
 * The County Sewer Mainline between Grayditch (Sewer Waystation) and Arlington Memorial Bridge.
 * The small radioactive sewer that is used as a Super Mutant base in Vernon Square.
 * The sewer south of Grayditch, northeast of Red Racer Factory, with some Ghouls and a Gun Case with a Missile Launcher.
 * A Sewer south of Arlington Library containing raiders, a big stash of chems, a set of Metal Armour and caps. A fairly easily missed dungeon.
 * Old Olney Sewers, a sewer system under the abandoned town of Old Olney.

There are also seven "Drainage Chambers" and two "Sealed Cisterns" for the nine Morse-code "Signal" radio stations.