Find the Water Chip

Find the Water Chip is a Fallout quest.

This is the first official quest, go and retrieve a new water chip for Vault 13. Although there is a time limit for this quest (150 days), there are many other side quests to do. However, this guide is written on the basis that the player will ignore the side quests and attempt to retrieve the water chip as fast as possible.

Vault 15

 * Exit Vault 13 cave entrance.
 * Travel to Shady Sands, which is located on path to Vault 15.
 * Acquire some rope.
 * Pickpocketed off of Seth.
 * Found in bookshelves, or traders.
 * Enter Vault 15 and use the rope on the broken elevator shaft.
 * On the second level another rope can be found in the locker in a side room on the way to the second broken elevator shaft.
 * Descend to level 3, enter the area were the command center should be, earn experience for discovering the destroyed command center.

The Hub

 * Travel to the Water Merchants, and ask them to send water to Vault 13.

Necropolis

 * Travel to the Necropolis and enter the sewers.
 * Travel to Watershed area.
 * Either convince Harry you are an highly advanced robot with a high speech skill, or attempt to sneak past.
 * Speak to the imprisoned ghoul, and then enter the vault through the cell (with an actual door) located next to the ghoul's cell.
 * Travel to the third floor via the elevator and take the water chip from the command center.
 * Return to Vault 13 and give the chip to the Overseer Jacoren.

Detailed Walkthrough
Overseer Jacoren tells you that Vault 13 is running out of water, and that you need to find a new Water chip. Exit the cave entrance and travel towards Vault 15. Along the way you will come across a town known as Shady Sands. While you can continue to Vault 15 without stopping, you would just have to come back anyways.

Shady Sands
What you need from Shady Sands is rope. The easiest way to obtain it is to steal it from Seth at the entrance to Shady Sands. However there are other ways.
 * Rope can be found on certain bookshelves in Shady Sands.
 * Can be purchased from certain traders.

After acquiring the rope travel to Vault 15.

Vault 15
The vault entrance is hidden in the unihabited shack. Open the hatch and descend into the vault.

There are a few Giant Rats in the area. Head towards the broken elevator, and use the rope on the opening. This will allow you to climb down to the second level.

While on the second level you will notice a room with a locker inside it. This room is on your way to the second destroyed elevator shaft. You need to open this locker to obtain more rope. Use this newly obtained rope to descend to the third level.

On this final level of the vault you need to enter the bottom right room, this is were the command center should be located. However it has collapsed, and there is no water chip. However you are awarded 500 experience for finding the destroyed command center.

The Hub
After coming out of Vault 15 empty handed, travel to the Hub. Which is located to the south of Shady Sands. After discovering the Hub travel to the Water Merchants area.

Enter the large building labeled Water Merchants, and speak to the Master Water Merchant. After you are done in the Hub travel to Necropolis.
 * (optional) She can send water to Vault 13 for varying prices. This will give you an extra 100 days if you are running short on time.
 * If you press her about Necropolis she will tell you its location.

Necropolis
Once in Necropolis use the sewers to get to the Watershed area. Find a building with some Super Mutants and an imprisoned ghoul. In order to navigate the area without combat, you can either try to convince the Super Mutant leader Harry, that your character is a highly advanced robot if you have a high speech skill. You can also attempt to sneak by him and his Super Mutants. After you have dealt with the Super Mutants, free the Ghoul prisoner (if he is still alive) and he will identify the entrance to Vault 12 in the adjacent cell.
 * If the prisoner is dead you can still enter the adjacent cell, it is easily identified because unlike the other cells, it has an actual door.

Once you enter the vault area you will encounter some ghouls. If you enter the area during the night they will be hostile. Regardless of what time you enter. You must travel to the third level of the vault. You can use the elevator this time. Enter the command center area, and you will encounter even more ghouls. However they will not be hostile until you steal the water chip from them.

After you obtain the chip head back to Vault 13 and give the chip to Overseer Jacoren.

Reward

 * 7500 XP
 * no time limit.