The wall of water is a character that is shown in the episode "Abstract". This creature acts as a wall to Jermaine's new house in the wasteland and is instructed to only let "the chosen one" in. When James tells Jake this is where Jermaine lives, Jake thinks he means "waterfall".
He appears to have been a giant wall of water with a face on it.
Hey! None but the chosen may walk beyond the wall of water.
- This character appears to share parallels to the stone wall brick Person from season 1.