Managing water and magma has killed too many of my dwarves. They are too slow, they approach from the wrong side, they seal themselves into chambers. Or I screw up on pressure and flood a bunch of stuff. Currently I have a fort with multiple biomes and a high aquifer and a low aquifer. My fort spans about 20 z-levels in between, alongside a volcano.
My solution is to tap the source once (ideally an aquifer at a high z-level), and feed it into a pressurized vertical stack so that I can tap into water on any level of my fort by channeling out a connection to the source stack. Nearby, I have a drain stack that dumps into (ideally) another aquifer further down. But you could use any source or drain.
On any given level, I can build a plumbing network, connect it to the source and drain, and have flowing water (pressurized if I want, unpressurized if I tap it so it flows through a diagonal).
This will also be great for magma! I'll tap the volcano once, and have easy (and safe) to channel magma sources on every level of my fort. The key is have stubs on each level with rock above them, and a three-level pattern makes that possible across all levels.
Example of plumbing stacks (source and drain):
# = wall, < = up stair, > = down stair, X = up/down stair, ~ = pressurized water, F = floodgate
Z0:
############
Source...F>#
~~~~~~~~~###
##########
Z-1:
Water Stack Drain Stack
###### ###
#X~~~# #X#
###### ###
Z-2:
### ###
#X# #X#
#~# ###
#~#
#~#
###
Z-3:
###### ###
#~~~X# #X#
###### ###
Repeat Z-1 ... Z-3 pattern as far down as possible
Z-n:
### #########
#<# #<~~~~~~~
### #~~ Drain
#########
Example of plumbing a level with flowing, depressurized water:
Basically, build the network, pop a floodgate near the source, then go upstairs and channel out the connection between source and floodgate. Wander out of your plumbing network, and open the gate. Note that the Z-level above also has a pressurized water stub, but it goes a different direction.
Z-2: (@ will be channeled from above)
### ###
#X# #X##
#~# ## #
#~# # #
#~# # ##
##@# #path ends up here...
##F# ####
#< #
## ##
#path to wherever...
####
Z-1:
###### ###
#~~~X# #X#
###### ###
###
####
# h# <--- channel the h from here, then go and open the floodgate
# ##
#>#
###