2w ago

Why is it okay for shit to go down the drain but not food?

I've heard multiple times that it's not okay to allow any food to go down the drain even with a garbage disposal, I guess because solids shouldn't go down the drain. But we put a shit ton of solids down the drain through the toilet and that seems to be fine. Does the toilet go to a different sewage pipe then the sink? Or does shit have different properties that make it dissolve better?

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Shit dissolves better. Food (generally) has more fats and oils that will stick and clog the pipes..
It's the same pipe.
- Combined with wet wipes, it transforms to Fatbergs. I really recommend the chapter about "Notable fatbergs"
  
  “The most notable Fatberg is Lord Eustace Fatberg IV. Lord Eustace had no hobbies as he was a non-sentient amalgam of human waste, wet wipes and fat lodged in a sewer.”
  
  Just don’t read about gutter oil afterward or you might immediately have some solids to throw at your plumbing.
  
  Why are the notable ones all European/Oceanic?
  Also hilarious that the only American one is also the only one that mentions sewage spilling out because of it.
  I thought America was #1. Up your game, USA. Get those fatburgs going!
- Speaking for your shit. I'm sure these some fat grease shit out the sticking and evolving in some pipes.

Food itself isn’t the issue - it’s the big chunks and oil/grease/fat. It’s better to pour it down the toilet, since the volume of water you flush it with is greater and the drain diameter there is larger as well (110 mm) compared to the pipes under your sink, which are usually 75 mm in diameter, sometimes even just 50 mm. Solids are also more likely to clog the P-trap under your kitchen sink.
Eventually, it all ends up in the same drain system anyway, so in that sense there’s no real difference.
Source: I’m a plumber.
- Since anyone can say anything online I'm gonna need to see some butt crack for verification.
  
  Careful what you ask for.
- I flush food down the toilet occasionally. Works great in places without garbage disposals.
- So if, say, someone poured bacon grease down the sink for several years until the sink stopped emptying, the solution would just be to pop the p trap off and clean it out? Seems simple enough. I always thought it would accumulate in the main line until that clogged.
  
  No, grease does accumulate throughout the entire sewage system. It’s the solids that most easily clog the P-trap.
  
  As a separate plumber, I would remove the p-trap and snake it until I can get good flow, then install new p-trap.
  From my experience plumbing and replacing drain lines, it’s the pipe from the kitchen to the main that backs up and clogs first. A kitchen drain will be 1 1/2” or 2” pipe, and a main will be 3”-4”. Problems come up when the drain isn’t supported properly, or the piping has a lot of warp with low and high spots. As it fills with grease it will begin to sag more in spots and exasperates any existing dips.
  I recommend people use enzymatic drain cleaners, not acid cleaners, once or twice a year with hot water to break down any grease deposits.

I'd also point out that the toilet pipe is significantly larger than than the kitchen pipe, and uses a multi-gallon, siphon-powered flush to help move it along. Your kitchen sink has none of these plumbing advantages. If you wanted to have a 3 inch kitchen drain and some kind of powered flush apparatus you might have a better time with food waste, but it's still probably not a good idea for the reasons other people have mentioned. A normal kitchen sink drain configuration, even with the assistance of a disposal, is still quite ill-equipped to handle that kind and quantity of waste.
- So don't poop in the kitchen sink. Got it!
  
  It's ok to shit in someone else's, just not yours.
- 3 inch pipe? I saw that movie... well parts

The type of food that's the worst for pipes is fats, oils, and grease. You should never put any of these down a pipe because they can solidify and cause pipes to burst. Restaurants are required by law to have a grease trap for any grease that inadvertently goes down to minimize the damage.
The occasional vegetable scraps going down a residential garbage disposal will not pose a huge problem, but keep out any fats, oils, or grease.
- If not for food waste, what else would you even use a garbage disposal attached to a sink for?!

As far as I know there are kind of 3 reasons:
Your sink pipes are smaller than your toilet pipes (by ALOT) which means that they clog easily
In some places your sink pipes and your toilet pipes go to different places. For example in some places the greywater (water from the sink) is let out in the open (which is fine as it is mostly just dirty soapy water) while wastewater (poopy) goes to the sewer.
Poop is usually not sticky and fatty while foods can be (imagine if you poured flour down the drain, it will become a sticky dough that will clog it)

It's mostly because of fatty foods. The fats/oils tend to solidify in the colder temperatures of sewage lines, ultimately causing clogged lines.
Our waste though has generally digested a large amount of that fat, whether it gets built up on your belly and ass or whether a lot of it gets expelled in the sweat.
Edit: Also, ideally, bacteria helps a lot with breaking down human waste and toilet paper, making the waste easier to flow through the pipes.
- Just wanna point out that dietary fat is not the same as body fat. You aren't made of walnuts, so walnut fat doesn't go straight to your belly. Just about all fat gets digested and converted into sugar, put in your bloodstream, and then, if there's excess, converted into body fat. To leave your body, it then gets converted back into sugar, gets used as energy, and then the CO2 goes back into your blood and exhaled. Sweating more doesn't cause fat loss, just water weight loss, and people losing weight aren't expelling it out by ass.
  Solid waste volume has surprisingly little to do with the actual food you eat. It's primarily dead bacteria, 50-70% by volume. While some food makes it through, it's mostly the nondigestable things full of fiber. And capsaicin.
  
  Just about all fat gets digested and converted into sugar
  This is not how lipids are metabolized. They are not converted to glucose right off the bat. Fats are broken down to monoglycerides to be absorbed, recombined to triglycerides and eventually chylomicrons, and transported to adipose tissue.
  https://en.wikipedia.org/wiki/Lipid_metabolism

Aside from what others have pointed out about solubility, sink drains, as I understand it, have a narrower pipe than toilet drains do, though once it gets out of the house it all goes through the same pipe either way, but I think that's a larger pipe than what's in the house.

Kitchen sink pipes are usually smaller more delicate than WC pipes. Most people throw food in their sinks, not their WC. All stuff ends in the same place, but the first pipes where stuff goes are different from each other

What’s the point of a garbage disposal if you can’t put food in there? You don’t need that to make liquids go down the drain.

Food is fine to go down garbage disposals, that's the point of them. Just don't put eggshells in them because the sediment they create is heavy and sits in your P-trap.

It depends on your plumbing. If your sink's waste pipe is large enough, and has enough slope, and you put enough water down the drain to wash all the solids through the pipe, then you can certainly put food down the sink drain.
In my house the kitchen sink's waste pipe is smaller than what the toilets use. And it makes a long, minimally-sloped run to the main sewer connection. That pipe will clog in a hurry if I put food down the kitchen sink drain.

No idea about clogging differences, but the toilet drain sometimes goes to a different sewer system than the sink drain. https://en.wikipedia.org/wiki/Sanitary_sewer
- This doesn't separate sink drains and toilet drains, it just prevents rainwater from diluting the sewage water. The water coming out of your sink is still considered sewage water.
- Your link isn't too helpful for what you're describing.
  All household wastewater (including kitchen) ultimately goes into the sanitary sewer in most places, if it comes out of a house it's all called "sanitary". The alternative to sanitary sewer is storm drain, which is intended ONLY for surface rainwater and usually never have any household hookups, except potentially from rain gutters on the roof or tile drainage below ground, but municipalities are often pretty strict about that as these systems are very important for managing stormwater and avoiding flash flooding.
  The third option, which I think is what you're getting at, is called graywater, and indeed you could have sinks and even showers plumbed into graywater drains, but never toilets, and it's often clean enough or can be filtered so that it can be re-used for flushing toilets, irrigating lawns and gardens or other forms of non-potable re-use that won't be bothered by things like soaps and lotions and bacteria and other things that might get rinsed off. This is common for RVs and boats and other situations where fresh water might be scarce, but very much less typical for household plumbing in most places in my experience, and there is rarely any municipal system hookup for it and the graywater is usually intended to be used on-site within the household plumbing system itself, but it can help divert or reduce wastewater into the sanitary sewer and can help reduce the use of clean potable water, so it is a good thing in general.

Are you flushing your food down the toilet?
- When I'm done with it, yes.

Not sure if this is true, but i've been told, when you flush food down the drain or toilet, rats living in the sewer might come looking where that delicious meal came from.
- I guess all those people with food disposals in their apartment are just rat infested🤣🤣🤣
- Rats go in toilet drains, too. We were unblocking a drain at work and I saw one going uphill, for second I was like “why’s that shit going backwards”.

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