Blue Prince: Reservoir Room Guide

The basement of Blue Prince is filled with secrets, lore, puzzles, and rewards. Once you have finally entered the Antechamber, you will get a key to the basement location, giving you access to all sorts of things you haven't seen before.

The Reservoir is one of the many underground spaces filled with items you'll want to see for yourself in Blue Prince. But in order to do that, you'll need to learn how to manipulate the water level and access the basement from more than one location.

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Blue Prince has a lot of items that the player can find. Here’s what all of them can do.

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By Huzaifa Haq

The Reservoir Room, Explained

According to the papers scattered around the whole house, the Reservoir is an underground location filled with water to make sure there is always water to fill up the different watery locations in the house and a place to drain that water when needed. For example, this allows you to drain the Pool floorplan in Blue Prince as well as the fountain in the front yard. You can also fill up things like the Greenhouse to water the plants there.

Blue-Prince-Reservoir-Room-Guide-Water-Levels

In order to drain the Reservoir or change the water level, you will need to interact with the Pump Room in Blue Prince. This room is one of the many blue rooms that are draftable in the house; it has four pumps that will allow you to move water around between rooms and locations. There is a chart you can find on a window underground that will teach you the different heights of water you will need to access everything the Reservoir has to offer you.

How to Empty All the Water From the Reservoir in Blue Prince

The Reservoir has fourteen levels of water. It starts at the very top, and you need to lower the water just one block to access the boat. It needs to be lowered down to the sixth slot to ride the boat to the Safehouse, and it will need to go down to zero to reach the bottom of the Reservoir. To lower the levels, you need to first draft the Pool in your house; this will add the Sauna, the Pump Room, and the Locker Room of Blue Prince to that day's drafting pool.

Using the pumps in the Pump Room, you can drain the water from the pumps 1 and 2 into the other rooms, and the two tanks can hold up to four units of water each. If you do the math, you will quickly realize that you can fit all the water from the Reservoir except one square in the other locations and the tanks combined, so you will need to do something else to empty the Reservoir completely.

Blue-Prince-Pump-Room-Guide-Schematic-Numbered

So, you will need to move some of the water from the tanks to the Reserve Tank in the Pump Room. Unfortunately, it doesn't work as is, so you need to connect a Power Source to the Pump Room. A Power Source room is a floorplan that is marked with Power Source, like the Electric Eel upgrade for the Aquarium and the Boiler Room.

If you look at the ceiling in the Pump Room, you'll see vent-like structures running along it. These are power lines, and you need to connect them between rooms to get the power into the Pump Room. There are several rooms that have power lines along the ceiling, including the Archive, the Weight Room, the Dark Room, and several others. There are also a bunch of other rooms that benefit from having power run through them, like the Laundry.

Blue-Prince-Reservoir-Room-Pump-Room-Powered

You need to connect the Power Source room to the Pump Room with these power lines or directly to get the power to the Reserve Tank in the Pump Room. Now that the Pump Room has power, you can drain up to six units of water into the Reserve Tank, giving you plenty of room to drain the Reservoir completely.

Level 13 Water in the Reservoir (Dock Level)

If you drain just one square of water from the Reservoir, which you can do by filling up a tank with three units of water, then pulling one more from the Reservoir, you can ride the boat. This ride will connect both sides of the Reservoir, so you can sail from one side to the other. Both sides of the Reservoir are accessible from other locations in and around the house, but this is a quick way to get back and forth if you need to. The boat starts on the south side of the Reservoir.

Basement Entry Point	Side of Reservoir
The Foundation elevator	North
The Basement tunnel	North
The Blue Flame elevator	South
The circular candle room	South

Level 6 Water in the Reservoir (Entry Level)

Blue-Prince-Reservoir-Room-Guide-Safehouse

When you get the water down to level 6, you will have access to another location. In order to get here, you have to lower the water down to exactly level 6 or 6 units of water, then head to the underground on the same side of the Reservoir that you last parked the boat. Next, hop in the boat, and the cutscene will take you to a white beach with a door in a massive rock wall. Inside will be the Safehouse.

Level 0 Water in the Reservoir (Full Drain)

Once the Reservoir is all drained of water using the instructions above, you will find a handful of chests at the bottom. There are a grand total of 23 of these guys, and they are all locked. You can't open them with the lockpick; you will need 23 total keys to open them all. Thankfully, if you know where to look, you will only need two keys to open all the Blue Prince locked trunks that actually contain loot. The others just give a hint as to which boxes have the items in them.

Big Spoilers ahead for the locked trunk puzzle at the bottom of the Reservoir.

Locked Trunk with the Allowance Tokens

You can open up enough boxes to learn which colors of boxes, memos, and box sigils are true and which are false, or this article can just give you the answer. One of the boxes has three Allowance Tokens that each raise your daily Blue Prince Allowance by two gold coins a day. In the diagram above, you will see that this is looking down on the Reservoir's bottom from the north side, so the map is upside down. The Allowance Tokens are located in box A.

Locked Trunk with the Sanctum Key

There is a second box with a prize inside: one of these has a Sanctum Key inside. If you want this special key for yourself, you will need to infer which box has what inside it through the notes, or you can read the spoiler here: The Sanctum Key is located inside the box labeled with an I in the map above.

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