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[zecro]

Has anyone ever built water towers to assist their elaborate drowning traps or showers? How tall should a water tower be to supply pressurized water to the underground complex? That is, how many z-levels does it take before pressure is so strong it stops mattering, or starts draining the reservoir too fast?

[Marconius]

Hmmm... I'm not sure water pressure is counted over multiple z-levels. That is, if you have a tower 5 levels high full of water and another one that's 2 levels high and you punch a hole in their sides near the bottom, the water spilling out will flow down the same way (which is not what would happen in real life).

I'm not exactly sure what you're asking though, could you clarify what you're trying to do? If you make a U-shaped structure (along the z-axis), the water will keep moving until the water levels are the same on both sides, as you would expect.

[darkrider2]

A water tower only needs to be one z above the room/area you plan on flooding. Since you will probably need a pump stack to fill the silo anyway you won't need to worry about it running out of water.

But one measly z level isn't very dwarfly at all, you need to build it with 20 z's and find a way to apply magma.

[gtmattz]

While refining my drowning depot I have found that 3 levels of equal dimensions as the area you want to fill will let the chamber fill fairly quickly and anything more is just additional dwarfiness.  That being said, I usually try to go for at least 7 levels for any future pressurized water needs (such as repeaters and other logic stuff which work best with pressurized water).  Something else to keep in mind is that the reservoir size will vary depending on your needs, so it is usually best to over engineer and have way more capacity than you think you might need just in case.

[zecro]

I was working on a design for my fortress, and since there are so many z-levels in DF2010, I decided to work in a plumbing system. Since the fortress is designed as a very tall underground cylindrical tower, each level with a plumbing system is sandwiched between a drainage level below and a plumbing level above.

What I want to do is to supply pressurized water to plumbing levels (using a lot of levers/floodgates/hatches to control the flow and pressure). After falling through the grates (or open hatches) on the populated level, the water will enter a drainage system and then will probably be recycled.

What I want to know is if water can have different pressures. Will water from a 10-high tower flow out faster than water from a 5-high tower. If so, how tall does it need to be for the water to flow really fast?

If it seems that this is a complicated scheme to drown everyone, it could be, although literally hundreds of doors and hatches would need to be destroyed for all the redundant stairs/access hatches/drains to become inaccessible.

[gtmattz]

You know, the best way to answer your questions (imo) would be for you to make a test fort, give your dwarves speed:0 no_eat no_sleep no_drink, make them all miners/masons/mechanics and start experimenting.  There is also a thread floating around here somewhere about the science of dwarven hydrodynamics that might help you better understand the way fluids work in DF. 

Ah here we go: http://www.bay12forums.com/smf/index.php?topic=32453.0

Another thing to keep in mind is that diagonals reset pressure, so if you want say, a waterfall in your dining room that is 20 levels below the top of your cistern, just have the last tile of the feeder plumbing be 1 tile off so that the water has to pass through a diagonal.  This will let the water flow out slowly and wont instantly fill your dining room.  This can also be used to fill a pool from the side etc.

[zecro]

According to that link, as long as there water is at least a single z-level higher, the actual volume of water matters, not how high it is.

That is to say, building a WIDER water tower would have the same effect as building a TALLER water tower, as long as the volume change was the same. i.e. the "pressure" effect of a 10x10x1 cistern would be the same as that of a 5x5x4 cistern.

Thanks! I think I just answered my question.

[Kanddak]

Precisely. Number of z-levels doesn't affect flow rate. It just affects the maximum level to which water will rise.
The only relevant unit to how much water you will get out of an elevated cistern is how many tiles of water are at a higher elevation than the area receiving the water and sitting on top of other water.

See the hydrodynamics thread gtmattz just linked and which is also in my sig. You are actually better off with a short, wide cistern than a tall, skinny one, for reasons which are a bit outside of the simple model I posted in that thread and which I haven't yet published.
See also: http://mkv25.net/dfma/movie-1621-pressurevsaltitude

[zecro]

I was going to perform that experiment, but now I don't have to, because you did it already!

The tl;dr is that altitude has nothing to do with flow rate, but volume does.

[Flaede]

I was going to perform that experiment, but now I don't have to, because you did it already!

The tl;dr is that altitude has nothing to do with flow rate, but volume does.

Except that the wider version will have more wasteage and stop the speedy rushing faster.The reason you use a tower is the lack of floor that will get in the way of an efficient system.