Why You Should Never Flush Your Own Toilet Paper on a Cruise Ship—And What Actually Happens When You Do

Cruise ships may feel like floating hotels, but their plumbing systems are nothing like what you’re used to on land

Let’s set the scene: You’re finally aboard that long-awaited cruise. You’ve unpacked your suitcase, you’ve got a cocktail in hand, and the ocean breeze is doing magical things to your stress levels. And then, after a quick bathroom trip in your cozy little stateroom, you do what you always do back home—flush the toilet paper you brought from Target.

Big mistake. Huge.

Flushing anything other than cruise-approved toilet paper—especially your own thick, ultra-plush, extra-cushioned brand—can cause real problems. Not just for you, but for the entire deck. Maybe even the whole ship.

Let’s talk about why you should never flush non-cruise TP, what actually happens when you do, and how that innocent little flush can create a very messy situation at sea.

Cruise Ship Toilets Are... Not Like Your Toilet at Home

To understand the issue, you first need to know that cruise ship bathrooms operate on a vacuum system, not a traditional water-based plumbing system. When you flush, the toilet creates a sudden whoosh of suction, using air pressure instead of gallons of water to carry waste through a network of pipes.

This method is super efficient—it saves water, reduces environmental impact, and allows plumbing to function on a ship where space and resources are limited. But it also means the system is delicate and unforgiving when something goes wrong.

According to Royal Caribbean Blog, the TP provided onboard is specifically chosen to dissolve quickly in these vacuum systems. Anything else—even something as harmless-seeming as a quilted two-ply from home—can cause clogs, blockages, or complete system failures.

So What Actually Happens When You Flush the Wrong Toilet Paper?

When you flush paper that doesn’t dissolve fast enough, it can get trapped in the narrow vacuum pipes, creating a sticky clog that doesn't just affect your toilet. It can back up the entire line of toilets connected to your unit—sometimes affecting multiple cabins.

Cruise lines like Carnival and Princess Cruises warn passengers against flushing anything other than ship-issued TP for exactly this reason. When something clogs the vacuum line, maintenance has to open it manually—and that means taking apart walls, floors, or ceilings in affected cabins. Not exactly the relaxing ocean vibe anyone signed up for.

And here's the kicker: you might not even realize you’ve caused a problem—until someone else’s toilet starts bubbling up.

It’s Not Just Gross—It’s a Health Hazard

Aside from the obvious ick factor, a backed-up toilet system on a cruise ship can create serious sanitation issues. The ship's waste management system is designed to handle high volumes of waste safely and hygienically, but a clog disrupts the entire balance.

According to the Cruise Lines International Association (CLIA), modern cruise ships treat wastewater to levels that often exceed land-based requirements. But they can only do that if the waste actually makes it to the treatment system.

Flush something that gets stuck, and now you're dealing with standing sewage, blocked cabins, and potentially quarantined rooms until the issue is fixed.

The Crew Will Know—And No, It’s Not a Secret

Here’s the thing most first-time cruisers don’t realize: If you flush something that causes a clog, the crew will know—and they’ll know exactly which room it came from.

The plumbing on cruise ships is monitored electronically, and maintenance crews are trained to trace issues quickly. If your cabin becomes the source of a blockage, don’t be surprised if you get a visit from the ship’s engineers—or worse, housekeeping with a mop.

As Cruise Critic explains, the “don’t flush anything but TP” rule is taken very seriously. That includes not just outside toilet paper, but wipes (even “flushable” ones), tampons, paper towels, cotton swabs, and tissues. And yes—that decorative tissue from your gift basket counts too.

So What Should You Do Instead?

It’s simple: Use the toilet paper provided, and toss everything else in the waste bin. Every cruise cabin bathroom comes equipped with a covered trash bin, and most are emptied at least once a day by your steward.

If the idea of throwing things in the trash makes you squeamish, don’t worry—liners are discreet, and the ship staff has seen it all. (We promise, they’d much rather empty a trash can than deal with a toilet backup.)

Bonus tip: If you’re worried about comfort, many cruise lines use soft, fast-dissolving paper these days—especially in suites and upgraded cabins. But even if it’s not five-star plush, it’s safe, and that’s what matters.

One Tiny Flush Can Ruin Someone Else’s Cruise

You might be thinking, It’s just one square of paper—what’s the big deal? The truth is, that tiny decision could cause hours of work for crew, inconvenience your neighbors, or even shut down part of a deck if the problem spreads.

As Cruise Hive notes, there have been multiple reports of cabins being temporarily closed or guests moved because of backflow from misused toilets. Trust us—if you think using a communal restroom is awkward, try explaining to your cabin neighbors why their toilet is out of service.

Final Flush: Respect the System, Respect the Sea

Cruise ships are marvels of engineering, but their plumbing systems need a little love and respect to keep things flowing. That means using only what they give you, and tossing anything else in the trash—even if it would be totally fine at home.

So next time nature calls at sea, remember: 

🚽 Use ship-issued toilet paper only

 🗑 Toss everything else in the trash can

 🌊 And keep the good times flowing—for everyone