No, absolutely not. That is a very bad idea. It won't work, even if it did work it would not be useful, and even if it were useful, the second something goes wrong, and something will go wrong, everyone will die. So... no.
But seriously, it would take a ridiculous amount of effort to get the water over to the barracks. Right now the building is in the opposite corner of the map from the pump stack and reservoir, which is still 2 z-levels or so below where you would want it. It's just too much effort for a death trap that probably won't work and definitely won't work twice, when the remains of my descending ceiling trap will be good to make an easily used drowning trap that takes fewer resources to run. (in case you are interested or I don't finish it in time, it involves chiseling out the middle of the block of stone which falls, adding a pressure plate to the path a bit before the chamber which attaches to a bridge above the chamber which is covered with water and falls directly into the depression while closing floodgates to lock the goblins in the depression. Pulling a lever in the fortress opens the floodgates allowing the water to drain out into the side trenches, from which a 2-pump stack carries it back to the top of the bridge. I need to work out the logistics a bit more, particularly to get the timing right, but it should let a group of ten or so goblins in at a time and then drown them, and then I need to figure out how to keep the dwarves out of it.)
In any case, just a short update with a cliffhanger again for now.
13 Limestone: I've begun constructing a trap to catch those goblins.
Where the children now stand, I shall build a support. I'll have a path run through the room into the fortress, then watch them come. When they reach the room...
15 Limestone: The first good news in a month!
23 Limestone: One of the children broke down today, started punching everyone in sight. The only way we could stop him was to put him down.
It is understandable. Both his parents, four of his siblings are dead. With nothing else to do, while waiting for the trap to be completed, I've ordered the continued work on the modular colony project below. Perhaps it will take the others' mind off what has happened.
19 Sandstone: Now, we shall begin our counterstrike.
Will the trap work? Will the goblins rush down into the fortress, and to their doom? Or will they burst through the doors, slaughter all in their path and claim bloody victory? Tune in next time... or something...
Kind of ironic; that kid was one of the miraculous double quadruplets from my last turn.