I can't seem to beat this, I've come close, but I'm always about 2-3 pieces short since the 3 drains are on all 4 corners of the room. Using the fixed pieces also forces you to close the loops.
Any help is appreciated.
I have beaten #23 in the Super-Hard "Rat" room if you want something in return.
Best Answer
This one took me ages too! It's a shame that Aqueduct doesn't save your setup when you solve a level, but anyway here is a screenshot I found online (linked in case you only want the hints below).
If you don't want such an explicit solution, I'll point out that (a) you don't need to use all the orange blocks and (b) the solution creates a sort of U shape. Good luck!