What happens in airplane toilet is a mystery most of us would like to leave unsolved.
In fact, from going thrice to the loo before boarding to staving off complimentary drinks served by flight attendants, most people try to avoid these dreary cubicles at all costs.
However, with hours spent in the air, there’s plenty of time to wonder about what happens once you flush mid-flight. Does it drop through a secret hatch that releases the excrement into the abyss or is it stored in a tank, and if so, is there some fancy internal plumbing going on?
To grasp how an airplane toilet functions, you first need to appreciate the mechanics of an ordinary toilet.
In the average home toilet, a bowl filled with water is the first step in a system that results in whatever is being flushed ending up at the wastewater treatment plant. In the act of flushing, either through the activation of a button or lever, a valve is opened to release pressurised water that’s discharged into the bowl to initiate suction.
This bowl empties, carrying the waste away into a septic tank or the sewage system by force of gravity.
The How Stuff Works website outlined that the issue with this method on an airplane (or a train, bus, or boat) is that the motion of the vehicle would cause water to splash out every time there was a little commotion. And, without any liquid at all, it would be impossible to use a siphon or gravity to empty the contents of the toilet bowl.
When you’re done with your business on a plane, you push a button that causes the excrement to be sucked down the toilet into a special tank in the back of the plane. When you land, special trucks with even more tanks arrive to vacuum the waste into a holding tank using hoses. The waste is then dumped into another tank, usually located near the airport, where it is mixed up with other waste from airport restrooms and eliminated.
This is where the myth is that you can get sucked into an airline toilet if you flush while sitting. In a previous interview with IOL this was debunked by general manager Southern Africa Air France-KLM, Wouter Vermeulen. He assured passengers need not worry about being sucked into the toilet as aircraft toilets have a closed vacuum system.
“When you flush the toilet, a powerful vacuum system located near the waste tank sucks down anything that’s lying over the hole and draws it down into the tank. The toilets and their vacuum systems are designed in a way that passengers won’t be sucked in,” he said.
The system actually has many benefits. For one, How Stuff Works states that it uses far less water than regular flushing: “Most vacuum systems flush with just 2 litres of fluid or less, compared to 6 litres for a water-saving toilet and up to 19 litres for an older toilet.”
Furthermore, since the system doesn’t rely on gravity, the pipes can be placed anywhere on the plane, Aerocorner explained on their website. This creates ease when installing new toilet systems on planes as the pipes can be put anywhere, saving space and avoiding the need to cut into floorboards to add internal plumbing.
Lastly, you may be wondering if the need for dropping waste from over 10km up in the air has ever happened? Well, the Thrillist reported that in 2012, Artie Hughes and his wife were on the deck of their Long Island home, when, from the sky, came a resounding splat. “Blackish-green drek raining down on them as a plane flew overhead near JFK. Hughes’s wife -- who was never named in media reports, luckily for her Google footprint -- bore the brunt of the freak incident.” The police were called where they then confirmed the grim reality that they had indeed been doused with human faeces.
How to ruin a Sweet 16 Party? Plane releases its "bathroom contents" above them! Story at 10 on @FOX29philly pic.twitter.com/65N8dqQPvA
— Brad Sattin (@BradSattin) May 19, 2015
The sludge is composed of Skykem (the blue liquid cleaning liquid aircraft use) and human excrement, often referred to as “blue ice”. “Once the plane reaches high altitudes, it freezes and pours out of the plane’s undercarriage. It dislodges when the plane approaches touchdown because the temperature rises at this moment,” said Aero Corner
However, this is such an uncommon occurrence that you likely never have to worry about your front deck being rained down with splashes of airplane waste.