How do I exit the cistern?

[Cambium29]

Hello, thanks in advance.

I'm in the cistern (watery room with the stairs, crumbled paths). I've shut off the steam valve and turned the other valves completely. Now, a water monster is skulking around and the room has red goo everywhere. The path back to the main door to enter/exit is blocked by a web of red ... stuff.

Is there another exit?