Eh, I just don't see those wheels providing enough torque that even several could muster this kind of pumping speed. Water in itself is not weightless, it's pretty heavy to move about and the parts you're working with are primitive. The pumps we have now put modern industrial pumps to shame.
I will not accept this statement without some proof. Calculate the flow rate of the dwarfish pump in cubic meters per second (dwarf time, not our time) and compare it to some industrial pumps.
Considering that a square can contain, as I've seen it put, "1000 dragons, as long as all but one are lying down" (or something like that), I don't think that we can standardize distance. At all. Depending on what you have in a square, it varies between tiny (one ring per square in a stockpile, unless you're using bins), to massive (thousands of tons of rock, if you're using a quantum stockpile).
Since a tick is
1.2 minutes, it takes 12 minutes for a dwarf to walk across one square. I'm not sure what speed humans move at (haven't bothered to check) but assuming that they take 10 ticks to move a square as well, as the average human walks
80 meters per minute, a square is somewhere in the region of 800 meters across. Obviously, if they move faster or slower than this figure will increase or decrease, but I think that this is a really good example of how little sense it makes to try to relate the game to real-world units. It does explain how hundreds of dragons can fit in a single square, though, but not why a cat can cause a traffic jam in a hallway.