Toilet Check Valve

check valve
A valve that closes to prevent backward flow of liquid
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction.
Limits the flow of gas to one direction only. Use a check valve between the bubbler and generator to prevent unwanted pressure build up in the generator, and a safety against a low level bubbler. A check valve, such as used on torches, is recommended.
A mechanical device in a pipe that permits the flow of water or air in one direction only.

toilet
A large bowl for urinating or defecating into, typically plumbed into a sewage system and with a flushing mechanism
The process of washing oneself, dressing, and attending to one's appearance
A room, building, or cubicle containing one or more of these
a room or building equipped with one or more toilets
a plumbing fixture for defecation and urination
gutter: misfortune resulting in lost effort or money; "his career was in the gutter"; "all that work went down the sewer"; "pensions are in the toilet"