To flush or not to flush

Hello from the US! Several people have asked me what the most challenging thing has been since being back in the States, and I must admit that it's flushing toilet paper. For 10 months, I've been "trashing" my toilet paper, rather than flushing. I knew before I moved to Brasil that trashing was the method of disposal, and I've spent time in Mexico, so it's not so strange to me. But why is it that we trash rather than flush? I've heard several theories:

1. Toilets and the sewage systems in the US are equipped with a small kind of garbage disposal at the end of the pipes that chops up the toilet paper and makes it able to break down more easily, and not cause a problem.
2. Toilet paper in Brasil (and Mexico) is made differently, and more difficult to break down.
3. The sewer system and the "pipes" are not quite the same quality as those in the US.

So, I've decided to do an informal pesquisa. Online I found this:

"Most treatment plants in the developing world function only partially / periodically; from your link: In Latin America about 15% of collected wastewater passes through treatment plants and that 15% claim is pretty optimistic. Moreover, given all the weird stuff people flush, TP is not in the slightest the biggest problem for treatment plants -- you wouldn't believe the things that come in through the pipes.

As suggested, it's at the consumer end, for what I think are three or four reasons. Water-flush toilets are surprisingly delicate creatures -- they need to be connected to drain pipes of specific sizes and laid at exact slopes (too flat and they clog; too steep and the liquids drain faster and the solids clog) and made from certain materials connected in specific ways; they need TP manufactured to specific tolerances (ever tried flushing a wad of paper towels?); and they need reliable and fairly pure water sources. In many houses in the developing world, several of those factors won't be there -- smaller outflow pipes, laid a bit too haphazardly and with too many bends; water supply that comes and goes; TP of uncertain origin; and so on.

But feces is water-soluble, so even a very imperfect system can tolerate poop being flushed down it; the less soluble TP (especially imperfect TP that might be too tough or too thick), feminine hygiene products, and other goodies will cause clogs where poop won't. Hence the trashcan next to the toilet and the signs saying "don't flush the paper!"

Of course, at some point that prohibition becomes cultural rather than simply practical, and even in houses with perfectly-functioning modern toilets that can take anything you throw at them, you will still see the TP bins.

And then I asked my dad, fount of much knowledge, and he says that it's because sewage pipes are not large enough to handle large amounts of waste that is not "natural" waste.

So all this to say, I would recommend NOT flushing while in Brasil. In our apartment, the toilet paper just swirls around the toilet bowl for 3 or 4 flushes, until it finally goes down. Yes, it's kinda gross to have a stinky trash can, but we change it pretty regularly, and either use plastic bags or clean with bleach to keep things clean. I don't think that many expats know about this little rule, because we've had lots of American expat visitors visit, and after doing their business, I find paper remaining in the toilet bowl. So here is your a friendly public service announcement from an American living in Brasil: Use the trash can!