Many people think toilet waste is disposed from airplanes by throwing it out of the plane while still in the air. And yes this actually used to happen in the past. The toilets in earlier airplanes were primitive and direct and passengers simply hurled the waste contents out the window onto the unsuspecting world below. Fortunately all these changed once commercial flying became popular and pressurized cabins were introduced.
Today airplane toilets are extremely different from normal standard toilets. Standard toilets use water and gravity to work. When the toilet is flushed the water siphons the waste then uses gravity to pull it into a sewer system or septic tank.
However this system cannot work on airplane since airplanes do not have a septic system to hold the waste. Placing water into airplane toilets would be impractical since the water would splash about everytime the plane moved and and make a mess.
What is used in airplanes is the vacuum system and only a tiny amount of water is used to clean the bowl and get it ready for the next person. In airplanes the toilet bowls are nonstick and contain a blue liquid called Skykem. This blue liquid helps in disinfecting the bowl and getting rid of any odors lurking about in the bathroom
When the toilet is flushed the vacuum effect happens and a trapdoor in the base of the toilet opens and Skykem fills the bowl.
The loud noise one hears when flushing comes from the vacuum sucking the contents out of the waterless bowl and not from waste materials being hurled into the air. The waste then travels through pipes to the back of the plane and remains within a special tank that can only be accessed from the exterior of the plane thus it’s impossible to clear the tanks during the flight.
Once the airplane lands the tanks are empties by special trucks. The trucks attach a hose on the aircraft and suctions the waste from the plane into another tank located in the back of the truck, where the waste is then disposed of along with the waste from the rest of the airport.
Once the plane’s tank is empty another hose is attached to both vehicles to clean the tank using a disinfecting product.
However there have been several cases where homes have been hit by blue ice falling from the sky. This blue ice is actually a combination of human waste and Skykem that freezes at high altitudes and leaks out of a plane’s undercarriage. Fortunately such cases are quite rare so you don’t have to worry about being hit by frozen toilet waste falling from the sky.