Shannen Findlay

What happens to your poop on a cruise ship?

What happens to your poop on a cruise ship?

Each year tens of millions of people around the world sail away by boat to their cruise destinations. Not many people know what happens when they flush the toilet though.

If you’re one of the many people who cruise every year then you should know what happens each time you flush the toilet.

It is easy to assume the sewage is just dumped out straight into the ocean, even kept below deck in septic tanks to be released somewhere else or even left until we get off the boat at the end of our holiday.

However, the answer isn’t far off.

Not so long ago, cruise passengers’ remnants were thrown overboard through “storm valves” attached to the ship.

These days, cruise lines must follow strict international maritime laws which requires vessels to be three nautical miles (5km) away from land before letting go of treated sewage, according to the International Convention for the Prevention of Pollutions from ships via MARPOL (Marine Pollution).

The environmental manager for Carnival Cruise Lines, Natalia Vecchione told that each ship has a wastewater treatment system as well as an environmental officer on-board to make sure all matters run smoothly.

So, while it may seem like the answer to where our bodily fluids go on a cruise ship is difficult, it actually turns out it is not all that different to our home sewage systems.

“When you flush the toilet, the wastewater is sent to the wastewater treatment systems on-board. The systems on-board treat the wastewater similarly to how it is treated on land. It goes through a multistage process including biological treatment and disinfection,” Ms Vecchione explained.

“Also, the treatment units are designed and approved to stringent International Maritime Organisation standards and they’re installed and operated in accordance with the manufacturer’s rigorous instructions and procedures.”

To put it more simply, when a passenger or staff member flushes the loo, all the sewage goes directly to the treatment plan on the ship, which treats and disinfects it until it is safe to drink and pump it back into the ocean – far, far away from dry land.

Ms Vecchione said Carnival Cruise Lines goes the distance, choosing to dump their sewage 12 nautical miles (22km) away rather than the expected three nautical miles.

“Once treated, when the ship is far enough from land, the treated water is discharged. And, once it’s discharged, the sea water one metre behind a ship is chemically indistinguishable from the water one metre in front of the ship,” Ms Vecchione said.

“Respecting and protecting the waters we sail in and the environment of the destinations we visit goes beyond being an operating necessity, it is also the right thing to do.”