With near magical powers at making things disappear with the touch of a flush, toilets may seem like the best place to throw out anything. “Seem” is the key word, because there’s a big difference between a toilet and a trashcan. It’s not just the flood on the floor, it can affect the whole system.
Think back, waaaay back to 2018 when a massive ‘Fatberg‘ blocked London’s sewer system (you’ll find similar sewer stories across Canada too, though not as grand). Anyhoo, back to London … this nasty mix of many unflushables, largely wet wipes and cooking oil, solidified into a 250 meter long, 120 tonne beast. That’s as heavy as a blue whale, though a tad less majestic. It cost millions to clear, (yes, like flushing cash down the toilet too). Interestingly, a section was sealed up and sent to a museum to commemorate what we should not do (or not doo-doo, groan).
Why are we talking toilets now? There has been a rise in floods at UHN hospitals and rehab centres stemming from people flushing the unflushables. These floods can impact patient care, and wastes a very precious resource: water. They’re also pretty embarrassing to the person whose flush became a flood.
First, let’s start with what we CAN flush:
- number 1
- number 2
- toilet paper
End of list. Everything else needs a different bin.
So, what should we not flush?
Let’s start with the greatest offender: wet wipes. Even the ones marketed as “flushable” wipes are NOT actually flushable! Wipes (both disinfectant and personal care) are made of textiles, like clothing. Textiles do not break down like toilet paper (TP) does. Not to mention, the chemicals in disinfectant wipes, ever popular in a pandemic, kill off the useful microorganisms needed to treat sewage waste water.
The next top offender? Paper towels which, despite a resemblance to TP, are too thick to flow through pipes. If you like to use a paper towel to open and close public washroom doors, please find a trash can or a compost bin for it afterwards.
As the pandemic persists (and persists, and persists), people are using more wipes, PPE, and paper towels, which is fine (sort of, that issue is for a different blog). Unfortunately, more are being flushed, which is not fine.
A surprise to many is that menstrual products are also best kept out of the toilet. That’s why most public women’s washrooms have a small disposal bin by the toilet. These are getting more high-tech and fancy, with footpedals or touchless waving systems to open and close. Granted, a simple container will do. (Hey UHNers, if any washrooms are missing this bin, particularly gender neutral washrooms where it may have been missed, please let Environmental Services know, or tell us at green@uhn.ca)
And now one of my biggest beefs with movies and TV shows … so many demonstrate the worst thing to do with leftover medication (prescribed or otherwise) … with a dramatic scene of flushing pills down the toilet. More than a clogging problem, pharmaceuticals can poison our waterways. This is an easy problem to fix as every single commercial pharmacy will take back your leftover medication and dispose of it safely.
You may have noticed oils and grease on the list of unflushables and may be thinking “who the heck has grease in a bathroom? What is happening in that person’s life?”. This problem likely comes from the kitchen, not the bathroom. If people throw grease, oil and fat down the kitchen sink, this meets up with the wrongly-flushed items later in the pipes. When grease meets wipes, that’s when the fatberg magic happens. There’s a better place for grease: cool it then scrape it in the green bin. High volume fryers likes restaurants can even earn cash by selling leftover cooking oil to grease recyclers.
In a nutshell, when these items clog sewage pipes, it causes flooding, interrupts the sewage waste treatment process, and contaminates our lakes and rivers. This is a huge waste of water, and fixing it is both difficult and costly (and probably pretty gross).
And hey, it may seem like the toilet can take care any problem, no matter how big. But the bottom (haha) line is this: only human waste and toilet paper should be flushed. Everything else belongs in the garbage, recycling, compost (or hazardous waste for medication). Not sure what goes where? Check out UHN waste rules or your local waste wizard.
It really helps to see the message reminder right at the source. Big shout-out to Niyat for creating this rather elegant and instructive poster, now in a UHN washroom near you (UHNers: contact green@uhn.ca if you need more).

Let’s keep our waterways safe and lush by learning what not to flush.
Excerpts from the original “Gripes about wipes in pipes“, by Niyat Gebreab, published September 24, 2020