Fix the Necropolis water pump

Fix the Necropolis water pump is a Fallout quest.

Thirsty Ghouls
After talking to the underground ghouls of Necropolis travel to the watershed area and then enter the sewers. Go to the back of this section of the sewers and you should find a pile of junk. Alternatively, you could already have grabbed the junk from a crate in Jacob's Weapon shop in The Hub Old Town. These are actually the parts that will fix the Water pump.

Get past the Super Mutant guards back in the Watershed area, by convincing Harry that you are a robot (speech), or by simply killing the Super Mutants. Go to the water pump and use your repair skill to fix the pump. If your repair skill is too low, you can travel back to speak to the leader of the underground ghouls who will give you 3 copies of Dean's Electronics. It may take a few tries for a low repair character, but once the pump is successfully fixed you will recieve 1000 experience. Now you can rest easily knowing that jacking the Water Chip won't cause the poor hapless ghouls to die of thirst (they simply die from another Super Mutant raid).

Set wants it fixed
An alterative way to get this quest is from Set. If you have already gotten the Water Chip from Vault 15 and are in possession of the "junk", Set will have his surly minion, Garret, fast travel you to the water pump. Garret will watch you attempt to repair the pump at gun point.