The Vault - Fallout Wiki

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The Vault - Fallout Wiki
Poseidon Reservoir
PoseidonReservoirExterior Location FO4.png
377160 20180814162843 1.png
377160 20180814162922 1.png
Worldmap Loc Img 138.png
Map MarkerPoseidon Reservoir
FactionsPoseidon Energy (formerly)
QuestsLearning Curve
Pest Control
Cell NamePoseidonReservoirExt
PoseidonReservoir01 (interior)
ref id0000e53f
00053834 (interior)
TerminalsPoseidon Reservoir terminals

Poseidon Reservoir is a location in the Commonwealth.


This reservoir not only distributed water from Lake Cochituate to the surrounding farmlands and towns, but was also a source of hydroelectric power, used by Poseidon Energy for its research facilities scattered about the Commonwealth. On October 22, 2077 there was a mass email sent to the entire staff detailing a change in their policies regarding Bring Your Child to Work Day. Normally, they wouldn't allow children into the plant; however, they decided to change the policy to allow two children at a time. If the worker were to bring in more than two children, they would have had to leave them with a caretaker outside the factory while the other two were taken on a quick tour.[1] Currently, the reservoir is in a state of disrepair, and is far more dangerous than it was before the War, with a pack of feral ghouls having moved in.[2]



A series of catwalks on the north side of the facility lead up to a maintenance area containing an armor workbench. A catwalk connecting to the room leads up around some central pillars.


The facility opens to a managerial office on the right, which contains a terminal that opens the doors on the ground that lead further in to the facility, as well as another armor workbench. A network of catwalks lead all over the room. On the ground floor in the southwestern room is a weapons workbench. The locked doors on the southeast end of the plant lead down in a room with some holding tanks, as well as a chemistry station.

Notable loot

  • A robot model kit (parts) is found in the Railroad cache; by going into the broken pipe on the south side of the plant and following it to an enclosure. The parts are on a coffee table.
  • The Poseidon Reservoir safe key is in the corner of the managerial office's roof, accessed by going up the catwalks and dropping down.


Poseidon Reservoir appears only in Fallout 4.


  1. Poseidon Reservoir terminals; Terminal
  2. Fallout 4 Vault Dweller's Survival Guide Collector's Edition p.353-354: "[5.01] POSEIDON RESERVOIR
    Poseidon Energy Reservoir not only distributed water to the surrounding farmlands and towns, but it was also a source of hydroelectric power. The power generated was used by Poseidon for its research facilities scattered about the Commonwealth. Currently, the reservoir is in a state of disrepair. The hydroelectric generators no longer operate and the water has become stagnant."
    (Fallout 4 Vault Dweller's Survival Guide Map)