Sewers puzzle

[dufake]

So, I'm in the sewers part and in the first room you enter I did both the puzzles on the left side and found 3 pipes to insert but no matter in which order I do nothing happens...Do I have to do something in the water room or what?

---

Nevermind, I figured it out.

I am stock at the same place.

There are only three pipes.
Even you make all the six switches right, nothing happens.

Head to the water room.
Find the four(or three?) switches. (remember to smash the bridge down.)

Here I am, no idea what to do now.