The Septic Tank is an area of the Sewage Disposal Plant featured in Resident Evil 2.
The Septic Tank is an "I" shaped passage, composed with septic tanks all around the room.
The door at the top left side requires four plugs to unlocked. The four plugs are King Plug, Rook Plug, Bishop Plug and Knight Plug that can be found in various area such as Library, Interrogation Room A, Cog Room and Art Storage Room.
Before the final plug can be entered in Scenario A, the G Young which killed Ben inside the Holding Cell had grown into a G Adult and therefore it must be fought before proceeding toward the sewer entrance. In Scenario B however, William Birkin who armed with a pipe will be face instead. Upon "Dying", William will fall from the passage.
|Door to North sewer entrance||It's tightly locked. The panel on the right appears to open it.|
It looks like a panel to release the lock. There are descriptions for the plugs.
"King plug insertion. Rook plug insertion. Bishop plug insertion. Knight plug insertion."
|Door panel (After all plugs has been placed)||All plugs are in place and the lock's been released.|