40d:Reservoir

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v50.14 · v0.47 · v0.34 · v0.31 · v0.28.181.40d · v0.23 This article is about an older version of DF. More Info · V

A reservoir or cistern is merely a holding area for storing water needed for drinking or other purposes*. This lets you take advantage of lakes without tapping all of it at once, or to get water from a river without flooding the whole fortress. You can get water from the ocean, but it's not drinkable without either a well or desalinization.

(* Technically, a cistern is constructed, while a reservoir is either constructed or merely dug, but with the exception of desalinized water there is no functional difference.)

Producing a reservoir does not involve constructing a specific building, but rather by hollowing out a great underground chamber, routing water to it, and ideally capping it with a well for easy access.

Why do I need one?

There are many reason to build a reservoir. Water which is "inside" does not freeze in winter. This means that your well will continue to function, providing water to your injured dwarves, and backup hydration should you run low of alcohol. Same with a fishing zone.

Other possible uses include...

• (re-)Irrigation
• Flooding traps
• Death chamber
• Controlled waterfall
• Swimming pool
• Obsidian farm

Finally, one may simply rest easier knowing that you have a ten years supply of fresh water to match your ten years pile of quarry bush leaves, and will live on even if the forces of darkness somehow block your river.

(Also, it has been suggested that in the future, brewing will require water.)

Operation

Open the outer floodgate to fill the reservoir. Close it once there's enough water inside. Open the inner floodgate to release the water. Never have both open at once!

Making a reservoir

Planning

Plan carefully where you want the water come from, and where you want it to go. Building next to a body of water is easiest. You can have the water flow down a staircase, or make channels for the water. Block off any corridors that connect to the water output. A simple door right next to flow will prevent water from pooling in the corridor.

Also, you need to place two levers to control the flow of water. It is easy to forget which lever connects to what. You might want to build a lever room nearby. Build levers parallel to the floodgates.

Digging

Mine out an area like this, one level below the ground. The diagonal kink is important! The area above it will be the reservoir proper. It can be any size you like, but make sure it only connects to the rest of your fortress through that diagonal opening. Water will flow out from below that kink, so make sure there's no hallways below that you don't want flooded.

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Floodgates

Build the upper floodgate at the very end of the reservoir chamber. Once it's in place, connect it to a lever.

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#	#	>	#
#	#	#	#

Once the first floodgate has been connected, build the other floodgate just behind the kink. Dwarves don't build on the diagonal, so this keeps your dwarves from trapping themselves. Connect it to another lever.

w	w	w	w
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#	X	#	#
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#	#	+	#
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#	#	>	#
#	#	#	#

Input channel

From above, channel into the water source.

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Output channel

You can have the water just flow down the stairs, or dig a channel just outside the outer floodgate. This cuts off access to the reservoir, so you can't re-jigger the floodgates. Hopefully, you will not need to, but you can build a horizontal grate or floor bars to make the channel walkable but still allow water to flow through.

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#	#	W	#
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Variations

Deeper reservoir

If for some reason you need to build a reservoir deeper underground, or further from the water source, you can connect the water source to the first floodgate by a stairway or tunnel. Add another kink before the first floodgate to avoid trapped dwarves.

w	w	w	w
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#	#	+	#
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#	#	>	#
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Customization

While the basics of a cistern are very plain, one can apply a great deal of personalization to your cistern. It can be completely cube shaped, rectangular, or circular. You can have a floodgate or hatchcover leading to a drain, perhaps a chasm, to allow you to drain and maintain your cistern. You may also want to pave the floor in case you have uncovered an underground river or pool, in order to prevent the growth of tower-caps. Finally, you might want to use pressure plates to automate the intake floodgate, keeping the cistern full (but not overflowing).

For detailed instructions on setting up a working well, see the well guide.

Fish-proofing

Draining from a large body of water can allow large and potentially dangerous aquatic creatures into your fortress. Installing a grate or bars across the water flow can keep them out. Note that bars will allow vermin-size creatures though, and grates do not. You can use fortifications too, but this slows down the flow of water.

Re-directing water flows

It's possible to re-configure a reservoir to channel water in a new direction. You can construct walls and floors to block water, or place doors and hatches.

Doors vs floodgates vs drawbridges

You can use doors and floodgates interchangeably. Drawbridges work as well - when they're raised, they block any passage they sit in front of, and this includes the passage of fluids. (This is expected to change in the future, so your doors might start leaking in the future.)

Magma Reservoirs

You can move magma around using the same basic principles. Constructions (walls, ramps, etc.) do not need to be magma safe, nor do pumps (so long as they are not submerged) - glass or wooden walls and pump components (blocks, pipes and screws) are fine*. Any furniture (specifically including doors, floodgates, and hatch covers) and mechanisms that will be submerged or "opened" to magma flow must be of magma proof materials.

(* Or usually are - it has been reported that long exposure to the heat of magma, from being directly adjacent to a large pool of it, will damage screw pumps to the point that they deconstruct. Not all players observe this, so more research is required.)