The way airplane toilets flush so violently, you can understand why some people are convinced waste is basically being ejected out of the plane.
Of course, this isn't the case, but you probably don't know how these toilets actually work - and the answer is more complicated than you might think.
Plane toilets are actually impressive bits of engineering, taking advantage of the pressure differences between the inside and outside of a plane to move waste around.
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Pressing the flush button in a plane toilet opens up a valve in the bowl - this valve connects to a pressurized pipe, which sucks the waste away. As explained to CNN by Nigel Jones, an aircraft engineering expert from Kingston University in London: "It’s like your vacuum cleaner - it sucks."
That suction is generated by the difference in pressure from the inside of the plane's cabin compared to the sky outside, which is why the process doesn't work if you're on the ground.
So, in reality, this vacuum-like effect is always happening while a flight is up in the air, but we only hear how strong it is when that valve opens and waste is sucked away.
Now, though, we come to the important bit - where does it go? Well, not out into the sky, that's for sure. That would be a messy way to fly around the world.
Instead, the waste is sucked through the plane to either the rear or front, depending on the model and the placement of the toilet, where it's collected in pressurized waste tanks.
These tanks are then emptied when required by specialized vehicles at airports, which doesn't sound like much of a fun job.
Tallying up how these toilets work, airlines are actually pretty proud of them - they tick a lot of useful engineering boxes. They use little to no liquid, for one thing, which is important since tanks of water would weigh a plane down and make it harder to fly smoothly.
Another big boost is they don't rely on gravity and can therefore flush no matter what position they're in, and the bowl that we all see in the toilet is also apparently coated with non-stick Teflon to make them even more reliable and cleanable.
While all of this speaks to some really great engineering, they're not without their quirks, and the narrow piping means that airplane toilets do reportedly get clogged pretty often. Despite the frequent warnings, it would seem that people still put napkins, wipes and nappies down them, which can cause some serious issues.