Okay look I thought I knew how a computer works but I really don’t. That’s the illusion of explanatory depth. I have it for everything: toilets (the water goes whoosh and the poop goes away; I have no idea how this happens), cars (gasoline makes the pistons go up and down and something something the car moves), and capitalism (people sell stuff and people buy stuff and this is bad, I guess?).
I wonder how many people can explain how a toilet works. You're sitting there every day, you have the ultimate information machine in your hand. It seems like you can almost reason it out from first principles.
Start with a hole in the ground. Problem: poop is smelly, the hole fills up and you have to dig a new hole.
Improvement: Throw the poop in the river. Problem: The river is far away, you have to walk in the rain.
Improvement: Build a structure to live in, throw the poop out the window, let the rain wash it away.
This technique was state of the art for a long time. People kept a container under the bed and in the morning someone, a servant if you were better off, would fling the "night soil" out the window. In the English-speaking world, it was a courtesy to shout a cute warning before spraying passers-by with human waste.
I had to look it up. In Edinburgh residents of tenement buildings would shout "gardyloo," short for “Prenez garde a l’eau!” before dumping their chamber pots out the window, possibly the source of the word loo.
Imagine getting up early to fetch the day's water from the village pump before a line forms, and you have to dodge a cascade of falling filth, and you appreciate that your neighbor was kind enough to let you know to get out of the way.
Eventually John Snow worked out that the village pump was killing people with cholera, so drainage was improved with sewers, open channels at first and buried pipes later. Water treatment is more advanced today, but sewers still rely mainly on dependable gravity. I'm not sure what happens when the toilet is too far from the water treatment plant to allow a continuous downhill grade; there must be some kind of poop elevator somewhere. Even here in the affluent D.C. area, I believe raw sewage is flushed into the river during heavy rains, because toilet waste and storm drains go through the same tunnels.
To save the trouble of handling waste, the sewer pipe can be extended into the home. A further convenience is a supply of drinkable water which can be used to flush the sticky mess down the pipe. I don't understand how the water supply works, I think I know where in the Potomac River my house water comes from, but I don't know where it goes after that. They add "chlorine" and "fluorine" but not the pure chemical elements, they pump it through undergroud pipes which sometimes rupture, water towers located at high places also provide pressure and reliable gravity flow. What steps are taken to prevent poisoning the treated water? How risky is polluted water? There was that building in New York City that had a murder victim floating in the rooftop tank for months and nobody (else) died.
We are almost at the modern toilet. For comfort, it is shaped like a chair, though some cultures still practice squatting. It's made out of porcelain, which makes it very heavy and subject to breaking. Why not lightweight plastic or fiberglass? Porcelain can be thoroughly cleaned and holds up to scrubbing. A removable seat is made of plastic or wood which absorbs heat more slowly so it does not feel as cold even when it is the same temperature as the porcelain.
There is still the problem of getting the waste to go down the pipe, and the problem of stinky sewer gas coming up the pipe. The clever solution is the P-trap, which is actually shaped more like a U, and also appears under sinks. Water fills the U and blocks sewer gas from coming up. And when poop drops into the water, it might be less likely to adhere to the toilet and the water can reduce odor.
Now we just need a supply of water we can quickly dump on top of the mess to shove it down the pipe. A bucket would work, but rather than taking time to fill a bucket we attach a tank behind or above the toilet and use a float switch to let it fill up, then turn off the water supply. When you yank the chain or push the lever, a flapper flips up from covering a hole in the tank and the water gushes down to hopefully send the waste away. The flapper has a clever design which holds enough air -- I realize I don't quite understand how it works but when the tank is full the water pressure holds the flapper down, then a chain attached to the handle pulls it up and out of the way until the tank water completely drains, and some water inside the flapper pulls it back down in place.
Our more modern toilets have pushbuttons on the top for small and big jobs, there is a float attached to a column under the buttons, and I don't know how the water flow is controlled. Like many newer technologies, the function is more opaque and when there are problems I am more likely to replace the whole thing rather than a part. In Japan the poop is teleported.
I remember what seemed like a ridiculous social quarrel when a new law restricted the amount of water a toiled could use per flush. People complained that they would have to flush twice, and they bought up the supply of toilets made before the limit, or imported Canadian toilets. Now that I'm older and grumpier, I am more inclined to complain. The only justification for the water limit is to save water. I find myself often flushing twice, or more. The smaller landing zone makes it more likely that waste will stick to the sides, requiring annoying brush work and yet another flush. I think it's reasonable to doubt whether any water has been saved, and to ask if it's possible that more water is used now than before, in addition to annoying people. I've taken many flow restrictors out of shower heads, and out of public faucets when I can. Those faucet restrictors may save water, because using them is so annoying more people will skip washing their hands. Switch the handles for a semi-reliable motion sensor and replace paper towels with a noisy electric blower and we're back in the John Snow era.