As they open the secret door, the adventurers can see what lies beyond. A large chamber, which is dominated by strange plumbing constructions, obviously the source of the sound.
In the center of the room a column of black foul water jets up through a clear pipe and out of the roof. Another pipe, which is coming out of the eastern wall, enters the base of the first one, pumping in streams of the foul liquid. All about the room are valves, gauges, petcocks, handwheels and other examples of arcane plumbing.