I was playing around with he mist generator idea and because it bothers me that it takes SO much space I was looking for a solution. I found my solution and it it elegant. You can literately place these where ever you want and the total water used is 7.
I use a windmill w/ one pump and a single channel 1x4. Also contained in this is a floor hatch and a pressure plate set to trigger at 5-7 water level.
So the materials at bare min if you but this on the top layer is.
x3 Mechanisms for pressure plate and link
x4 Logs for windmill
x1 log for floor hatch
and what ever eles you need for your specific layout
I have it set up as a tower so alot of this design can be cut you just need the two top layers.
EDIT:Another thing I forgot to mention is the fact that the screw pump must pump from the floor hatch tile. You also have to have an area for the screw pump to pump the water to or it does not work, I.E the Buffer at the end.
z-0
Just ground level of the tower walls and a ramp.
z-1
Same thing as level 0
z-3
This is the functional area of the mist generator, With the screw pump and floor hatch.
z-4
This is the power source.
The water flows to fast when your doing the initial setup so I used dfhack//liquids command to set the liquid in the channel in this example. I can envision how you could use this from a source with unlimited water or a river or such. It is alot more compact than the mist generator with 4 pumps and the amount of water dropped is 0 once the system is running. The trap flips over about every 100 ticks of the game which generates a fair amount of mist.
I tried to see if using the trap door would work by it's self and I can conclude that is is impossible for it to work as such. When the screw pump is introduced into the equitation it works as intended and no water is dropped from the system ever.
You can make this design as wide as you want as long as the input tile to the floor hatch is only coming from one direction. If there is more than one possible way from the water to exit it will leave to rapidly for the screw pump to pull it back. That is why the system uses a 1x4 area to operate.
EDIT: Forgot to mention that is requires 7 total water for the 1x4 system.
EDIT:Changed the photos 3-4 to have text descriptions because of ma graphics pack.
Also it is vitally important that you have the two buffer zones one in front of the screw pump and another behind where the floor hatch is.