Sewer monster?

I think, I think I think that this is a show I've been looking for for ages. The only episode I ever saw had this sewer monster, like the Flukeman from Fring and X-Files, causing horrible shenanigans. He had this wicked claws that he would tap on the sides of the pipes, kinda like echolocation, and at one point killed or turned into some guy down there, because this guy always wore a distinctive jacket, and when they found the monster, it was wearing that jacket. If anyone knows for sure, that would be awesome, because I really want to watch this again, but don't want to spend another hour chasing links. That episode scared the bejesus out of me.