[SPOILERS] Only about half way through, but it's brilliant!

[Frontcannon]

Finally, I am too intrigued by this to not mention it, but you know the area in the Sewers, where you have to turn 3 wheels to drain the sewer? There's a faint murmur coming from a blocky structure in there (the game even points this out), but once you've drained the sewer, it says 'the voice is silent'. Now, don't tell me what's going on here, but is it revealed what the hell is going on? Or is it another oddity of Castle Brennenburg?

That's the Cistern, and yes, that's an interesting point. My theories are that you are drowning a person trapped in that chamber, as the cries increase but go silent with the final valve :|

Maybe it even has something to do with the water lurker, a ritual to make it appear or extend the time it can spend in this world?