The sewer is a small underground area located to the southeast of the Arlington Library and is divided into three levels, with two guardrooms and a locked storage room on the bottom level. The storage room can be accessed by a terminal and contains a safe, an armor crate, and two ammunition boxes. The sewer also contains several hostile raiders of varying levels.
- One of the raiders may be found in the corridor upon entering the sewer and will run downstairs instead of engaging the Lone Wanderer. However, when they go downstairs he is ready with several other raiders to fight them.
- The sewer does not appear on the main map as a location, but the entrance is clearly marked as "sewer" on the local map. The entrance is a single door at the bottom of a flight of steps.
- The easiest way to locate this area is to fast-travel to the Arlington Library, head south to the Talon Company outpost, before finally heading directly east. Alternatively, if the Point Lookout add-on is installed, fast-travel to the Riverboat Landing and head west; although one might observe Talon mercenaries at the far end of the street, they should be able to reach the sewer without being spotted and engaged.
- Despite the fact that it's inhabited by raiders, there aren't any bodies hanging or graffiti on the walls; it looks to be almost intact, apart from some fallen shelves and boxes.
- The raiders here re-spawn every three in-game days.
The Arlington sewer appears only in Fallout 3.