A chemical toilet is a special toilet that uses chemicals to treat and deodorize waste. It is different than a traditional toilet used in most homes, which uses water to flush the waste away. These toilets are usually found in places where traditional plumbing is not possible.
In every chemical toilet there is a reservoir that stores special chemicals, typically ammonia compounds, that work to break down human waste. While the chemicals in the toilet do make the waste relatively odorless, they do not completely disinfect the waste. Human waste retrieved from this toilet can still harbor dangerous bacteria and other microbes.
Reservoirs in chemical toilets are emptied and replaced once they reach their fill. Many times the contents have to be dumped at special sites since they cannot be dumped into the general sewage system or into most septic tanks because of the chemicals they utilize.
Since a chemical toilet is often a waterless toilet, they are very convenient to use in areas where water cannot be easily accessed or is in limited supply. All port-a-potty toilets are chemical toilets. These portable bathrooms are very common on construction sites where plumbing has not yet been installed or at large concerts and other events where the number of people attending could quickly overwhelm the built-in bathrooms.
Some remote cabins use chemical toilets, as do many RVs and mobile campers. Many RV parks even have specially-approved dumping sites made specifically for RV owners to dispose of their full toilet tanks. These tanks are usually fairly small and can be dumped by hand.
Airplanes use a variation of the chemical toilet called a vacuum toilet. This waterless toilet employs both a powerful vacuum flush that removes all the waste left in the toilet. A small portion of the chemical agent also passes through the bowl when it is flushed to kill odor. A vacuum-assisted toilet is used in airplanes because using water would be impractical; turbulence or any sudden movements by the plane could make the water splash out.
The waste from the airplane toilet is stored in a chemical tank inside the plane. Although urban legends exist about planes dumping waste out of plane while in flight, this is not the case. In reality, the chemical tank is emptied and filled again by a special service cart after the plane lands at the airport.