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A water purification control computer system chip. Looks surprisingly like the chip that your Vault needs.Fallout in-game description

The water purification control chip, usually called just the water chip, is the cornerstone of the Vault-Tec Corporation's water purification systems installed in Vaults. The events of Fallout begin after Vault 13's only water chip breaks, and the only means to compensate for the diminishing water supplies is to leave and find a new chip.


The chip that controls the system is a fine example of 21st century electronics. It is a large circuit board with embedded vacuum tubes that regulates the filtration systems inside the water purifier and monitors the output for signs of contamination.[1][2] While the water chip can be jury-rigged for small scale water purification,[3] it is specifically designed to interface with vault water computers (via a specific slot and jack; the chip still requires independent power supply through its own cord), making it useless for large scale water purification without a vault.[4]

While it is theoretically designed to last, the chips were manufactured by a low-bid contractor, resulting in poor quality and a high failure rate. Such was the case with Vault 13 in 2161, made worse by the fact that the process was too complicated for a workaround system.[5] However, they are easily replaced: Chips are interchangeable and work in any Vault water computer, they just require a self-test and reboot after connecting.[6] The fact that they were shipped in boxes of five chips each is further testament to their expected failure rate.[7]

Vault 13 did not have surplus water chips due to a clerical error. A shipping mishap resulted in Vault 8 receiving additional water chips that Vault 13 had ordered in place of their second allotted Garden of Eden Creation Kit. The GECK was instead shipped to Vault 13.[8]


The water chip is the MacGuffin that kickstarts the plot of Fallout and provides the impetus in the first act of the game. It has no additional role in the game beyond delivering it to Vault 13 to remove the initial time limit. In Fallout 2 it's a miscellaneous item found in bulk in the living quarters of Vault 8.


  • Fallout Vault 12's command center, in a computer.
  • Fallout 2 One can be found in a locked footlocker in Vault 13.
  • Fallout 2 A grand total of 420 chips can be found on the second floor of Vault 8, in crates in certain rooms that can only be opened with a high Lockpick or Strength.

Behind the scenes

The visual of the waterchip just evolved into a visual joke while I was modeling it - I thought it would be funny to be showing the simplest, most basic motherboard type thing while the overseer was describing something so complex they couldn't hack together a workaround. That was how a lot of the design went on those things - we'd just come up with something we thought was funny while we were filling in the details. A specific detail I've never seen anybody mention is that the schematic behind the waterchip is actually for a Moog synthesizer.Leonard Boyarsky
  • Technically, the water chip is not a chip at all. The term is reserved for devices using integrated circuits, an invention that has never really caught on by 2077, printed on circuit boards. The water "chip" is a large processing unit built on a full metal chassis with thermionic vacuum tubes.
  • The blueprint shown in the background of the intro is actually a schematic diagram for a Moog synthesizer.[9]
  • In Fallout 2, the Guardian of Forever special encounter allows the player character to break the water chip and set the events of Fallout in motion.



  1. Kane: "{156}{}{A water chip? Never heard of it, we only sell drinks. Go see Bob's Iguana Bits, if you're hungry.}"
    The Vault Dweller: "{157}{}{It's an electronic device that regulates the filtering system of a water purifier and monitors the output for any contamination. Mine's broken and I'm looking for a replacement.}"
  2. PRO ITEM.MSG (Fallout): "{5500}{}{Water Chip}"
    "{5501}{}{A water purification control computer system chip. Looks suprisingly like the chip that your Vault needs.}"
  3. Vault 101 terminal entries; Vault 101 medical data system, Experiment PP216
  4. The Vault Dweller: "{104}{}{Do you have a water chip?}"
    Martha Rastello: "{112}{}{Water chip... hmm. Oh, those old Vault purifying control chips. Well, I'm sure I speak for the entire town when I say you won't find one here. Without the proper equipment they're worthless. Only a Vault, or maybe Necropolis would have any use for one. Why do you ask?}"
  5. The Vault Dweller: "{105}{}{Do you have a water chip?}"
    Paul: "{134}{}{A Water Chip? The ones from the old Vault-Tec shelters?}"
    The Vault Dweller: "{135}{}{Yes!.. Do you have one?}"
    "{136}{}{No. Those things were junk, they were prone to failure. We don’t deal with purifying our own water here. We have water delivered by caravans from the Hub.}"
  6. Jacoren: "{156}{Over_31}{Okey-dokey. One moment, the chip is initializing. Here - here - here - There it goes . . . Self-test is green . . . re-boot is good . . . Hah! It's working! And it looks like we have a winner! Haha! [The overseer sighs with relief.] You -- you've saved us. You've done it!}"
  7. PRO ITEM.MSG (Fallout 2): "{5500}{}{Water Chip}"
    "{5501}{}{This is a Vault-Tec water chip. They are typically packaged in groups of five to a box.}"
  8. Vault City central computer: "{241}{}{Cross-reference the GECK shipment information.}"
    "{244}{}{Due to a shipping error, it appears Vault 8 received a box of surplus water chips intended for another Vault. The other Vault most likely received Vault 8's second GECK.}"
  9. RPG Codex interview with Leonard Boyarsky