Walter's Scrap Metal

 refers to an unmarked and repeatable quest in Fallout 3.

After the pipes in Megaton are fixed, Walter offers to buy Scrap Metal from you to maintain them.

Reward

 * Walter gives you 10 bottlecaps per Scrap Metal; if you decline payment, you will receive positive Karma (20).
 * You also get a 5 XP reward per Scrap Metal you give Walter.

Bugs

 * Walter is known to disappear, making the continuation of this quest impossible. This is purportedly corrected in Patch 1.1.0.35.
 * If you bring Walter some Scrap Metal (tested with more than five Scrap Metal units) there is among the possible statements : "Eden wanted me to contaminate the water with a virus", which is something you can tell to Elder Owyn Lyons when coming back from Raven Rock.