Why Airplane Toilets Are So Loud: The Engineering Behind The Sound

  • By: pdstamp
  • Date: January 16, 2023

If you are new to travel, sitting in an airplane might seem daunting as is.

However, coupled with the loud noise that airplane toilets make, your experience may seem less than ideal. However, there’s a reason why airplane toilets are so loud.

And no, it isn’t because they want to scare you off using it!

Airplane toilets are loud because they use the pressure difference present between the inside of the cabin and the outside to move waste to the waste tank through pipes. The air pressure difference, therefore, causes flushing to make a noise of about 100 decibels.

However, that’s not all there is to an airplane toilet. They’re also very small in most airplanes inducing claustrophobia, and cannot be used in certain situations when flying.

In this article, we’ll go over all these reasons and tell you exactly why that is. 

How Do Airplane Toilets Work?

Understanding how airplane toilets work is a crucial metric for identifying why they are also very loud.

The bowl of the toilet in an airplane does not contain water. So, unlike a traditional flush which has water carry waste to sewerage, the power of gravity is used instead.

Simply put, as soon as you flush, a partial vacuum is created due to the pressure difference between the inside of the cabin relative to the outside atmosphere.

Once that happens, waste is sucked from the flush to the plane’s rear (where the waste tank is located) through pipes.

The waste is transported with a velocity of about 300 miles per hour.

That’s faster than the quickest car in the world, the Bugatti Chiron, which clocks in at about 261 miles per hour. So, with all that speed comes the big whoosh that we’re accustomed to. 

If you thought you were the only one who found airplane toilets extremely daunting due to their noise, don’t worry, others have too.

In fact, researchers from Brigham Young University are creating a new vacuum-assisted toilet that produces about 20-50% less noise than current flushing systems implemented in modern airplanes. 

Why Don’t Airplane Toilets Use Traditional Flushes?

Traditional toilets use a siphon concocted by moving water to pull waste down into your drain.

Theoretically, these can be implemented on an airplane. However, the amount of water needed is significantly higher than a vacuum-based flush, which airplanes are currently using.

Airplanes, or any flying object for that matter, need to be extremely cautious of their weight. So, implementing a traditional flush would lead to the need to store a lot more water than what is currently done to practically achieve the same purpose; flushing. 

Here’s a table that helps put things in perspective:

MeasurementsVacuum Flush Siphon Flush
Gallons Needed Per Flush0.55 gallons per flush3.5 gallons per flush
Gallons Needed Per Plane (1000 Flushes)550 gallons3500 gallons
Source: ThePointsGuy

With a difference of almost 84% in total water storage, it makes sense as to why airplanes are still using the loud vacuum-based system rather than a traditional toilet. 

Where Does Airplane Waste Go?

Contrary to popular belief, aircraft waste is not dumped on the ground whilst the plane is in the air. (Apologies for spoiling the fun!)

It is transpired through pipes to the rear of the aircraft, where one tank (or multiple depending on the size of the aircraft) is located.

This tank cannot be opened by the pilots or from the inside. So, even if the pilots want to dump the contents mid-air, they can’t. 

Instead, the opening of this tank is located externally.

Once a plane is safely landed on the ground, a special truck will use a large pipe to drain the waste tank of all its contents.

However, depending on the flight, the tank may not be emptied every time. However, once it is emptied, another hose is clipped onto the airplane’s waste tank, which disinfects the entire tank.

Why Are Airplane Toilets So Claustrophobic And Small?

Airplane toilets are small for a number of reasons, here’s why:

  • Make Space For More Seats: Plain and simple, the smaller the toilet, the higher the chances for an airplane manufacturer to fit in more seats. Since there’s no regulation on the minimum bathroom size on an airplane, airlines tend to reduce the size of toilets as much as possible.
  • Function Over Form: Airplane toilets aren’t meant to be places where you can take a shower and relax after a long day. Therefore, they only have the bare essentials to get the job done. This leads to them being much smaller in size than the average toilet back on ground.
  • They Don’t Generate Profit: Let’s face it, we don’t pay airlines to go to the loo. So, they have no incentive to pave the way for bigger ones. A smaller toilet leads to more space to pave the way for something that does generate profit – more seats.

How To Make An Airplane Toilet Feel Less Uncomfortable?

Now that we’ve understood exactly why airplane toilets are loud and small, is there a way for us to get a better experience?

Well, yes! Here’s a quick look at some tips that’ll help make your next journey to the lavatory in the sky a bit more bearable:

  • Wear Earplugs: We can’t stress this enough, the loud noise can be overbearing for anyone. It is better to wear earplugs so you don’t hear the noise of the vacuum flush as much. 
  • Time Yourself: You probably feel anxious about going to the lavatory if everyone sees you. Therefore, we recommend going at times when either food is served or everyone’s fast asleep. In both cases, you’ll be able to make a trip to the loo without anyone noticing.
  • Move Light: If you are wearing layers of clothing when going to the toilet in an airplane, you’ll feel suffocated inside. Therefore, even if it’s a bit chilly, we recommend stripping down to the bare essentials so you can make the most out of the little space you have in there.

Final Thoughts

Remember that traveling is an uncomfortable experience for almost everyone and the passenger right next to you is probably as worried about going to the toilet as you.

So, instead of stressing about it, wear an earplug, take your jacket off, time yourself and give yourself that much-needed break.

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