Garrett went on to reveal how much waste builds up on long haul flights.
“On a 747 or a long haul flight toilets can be flushed over a thousand times,” he said.
“Creating over 320 gallons (over 1200 litres) of waste. That’s a lot.”
Garrett’s post has attracted 4 million views, with many people thanking the pilot for the explanation.
“That’s my question since I was a kid,” one person said.
While others commented that they believed the old myth of waste is dumped from the sky.
“I always thought (it) flew out of the aeroplane and it hit someone in the face later on,” one wrote.
“Ok, now I know. I use think it does that down over the sea lol,” another said.
“What I thought it just flys straights out of the plane.” a third wrote.
“My mum always told me it used to be dropped from the plane but it would disintegrate before it hit the bottom,” a fourth said.
Some were surprised that people still believed waste is dumped out the bottom of an aeroplane.
“It’s still perplexes me that people think it just dumps out of the plane,” one said.
“Wait ppl (people) actually think it dumps out below? So they think there’s (waste) falling out of the sky?” another questioned.
Leading one person to admit: “I did”