How is 2.5 gallons enough water to get our waste from the toilet to the sewer, and eventually to the water treatment plant?

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Edit: OK, I am not sure where I got 2.5 gallons from because it turns out standard toilets in the US are 1.6 gallons, as the comment below states. It still seems crazy to me that 1.6 gallons can push waste all the way from the toilet to the sewer. I feel like it would stop at some point and need more water to get to the street.

On a side note, I find plumbing and water treatment fascinating.

In: Engineering

It just has to make it to the sewer which is easy enough especially as they’re usually sloped on the way there. The sewers already have other water coming from any number of sources plus may be fed a trickle at the head of the pipe to keep things moving.

The water acts more like a lube and volume enhancer for the turds, Gravity and pumps pull and push the turds all the way to the treatment house.

When the sewer from your home its piped having pitch downwards and used a turn at the end of the line rolling into the city sewer to increase speed much like a small waterside. Then the city sewer is pitched as well and has the quantity of everyone else’s house feeding into it as well. In most cases it leads to a pump station then pumped from there to a treatment center.

Isn’t 2.5 gallons almost 10 liters?

Normal toilets flush with either 2 or 4 liters, right?

I mean, that’s what my 25 year old toilet does?

You’ve also got gravity, other water from all sources working together to flush the waste into the sewer pipes. There isn’t a separate connection for toilets and for sinks, showers, bathtubs, etc.

Everything is sloped down hill until you either get to the treatment plant or a pumping station. More importantly, it doesn’t have to make it all the way there in one go.
The toilet flush has to get the solid waste as far as your main drain to the street – not even to the street sewer, just your main drain is enough. From there, every time you wash your hands or do the dishes or take a shower you are flushing more water down the same drain. Provided it doesn’t manage block up, this will keep things moving enough and once you’re into a main sewer there will be enough flow from different sources that there’s always some water moving through the system

Isn’t it possible that it doesn’t make it on the first trip? A couple pee only flushes could help out get there eventually?

Same way a 3 foot wave can take out a grown man. I mean, it’s just the right amount of everything. Slope, time to travel between wastes, size of everything, and all of the ways to check if there’s a blockage every step of the way. Took years to perfect the system we have now and it’s only getting better.

Kinda the same way that a waterslide works to move a 180lb human to the bottom, as long as the water is mostly behind and under the turd it’ll keep on slipping

Your poo basically liquifies from the agitation of going through the toilet trap as well as the typical vertical drop in the sewer pipe drop to your sewer line. Then it makes its way to the larger diameter sewer pipe in your street. All the water from showers, sinks and other sources add to the liquified poo making it a very liquid emulsion. The slope of the sewer line is critical. It should either be a slight slope for laminar flow or a vertical drop. A steep slope like 45 degrees actually causes clogs and is avoided.

I want one of those commercial toilets in my house. I will *never* work at a place that does not have a commercial toilet ever again.

I have super-sized shits, and have clogged up toilets many times. Flush 5 or 6 or 10 times and it just does not go down. And then give up and let it sit there, ready to ambush the next person going into the shitter.

One place I worked at, the building owners were so cheap that the janitorial staff came in once a week, so if I took a shit on Friday, it would be in the toilet until the next Friday when the janitor came in again.