What makes one toilet perform better than another?

I’m talking about unpowered household toilets with no fancy features like a vacuum flush. Just your standard toilet that works by emptying the tank into the bowl to flush the contents.

All toilets drain to a waste line that is the same diameter. What makes one toilet flush better than another? We have toilets in our house that are about 25 years old that work fine most of the time but get easily clogged, even with a normal amount of contents in the bowl. We got a new Toto toilet that has a very fast flush, does not seem to dump as much water into the bowl, but that thing never gets clogged and seem to handle anything.

What is the difference in how toilets work that can account for this?

Even in toilets without power assist, there’s apparently a lot that can be done with the design of the interior (particularly the piping that goes from tank to bowl, and from bowl to waste line) to create a powerful flow of water, even with the “low flush” water quantity.

I have a Toto toilet too which uses what they call “Tornado Flush” which is different than the usual home toilets most of us have had in the past.

Like you I have never had a clog (knock-on-wood) although I fear the day my BiL visits. He is a very big man and has been known to clog toilets with some frequency.

They claim their system is more effective than the standard toilets we all grew-up with. How much is truth and how much marketing I cannot say. I can say that a second flush because not quite everything made it is much less common on this toilet.

It does not rinse the bowl as well as previous toilets I had though so bowl cleaning happens a bit more often than before. Maybe that is partly due to this one being low-flow. But it does seems to provide some suction action in the flush pulling the contents in.

I dunno. It works for me.

A few years back I replaced two of our toilets with Comfort Height models.

They are Champion brand with a 4" flush valve. The water flows from the tank much quicker than other models available at the time. I’d been on some pain killers before my hip replacement and have not managed to clog either of these units at all.

I got this when I replaced my toilets. So much better. Due to COVID I have been at home a long time and not in the office. When I went back to the office and used the bathroom there they were not comfort height (probably 50 year-old toilets). My brain thought I would be sitting sooner than I did. Nothing bad happened but that was embarrassing even though I was the only person there.

Kinda like when you think there is another step on some stairs but it isn’t there resulting in a bit of flailing.

The one other thing I got used to with the new toilets are soft close lids. I was at a friend’s house and using the bathroom and my brain just assumed soft-close. But they weren’t and the lid slammed down. Again, no harm done but embarassing.

Low water volume toilets that actually work well required a lot more testing, design work and a few extras.
Old ones got the job done with water volume. But they could clog a lot because they did not have some of the new features.
The exit from the bowl route in good new toilets have excellent flow and are completely glazed. Old ones not so much.
Old ones depended more on just a large long lasting flow to clear them well. But they were prone to constriction, bad angles and non glazed ( rough ) pathway.
If you had the same large volume of water per flush as an old toilet, in the good new designs, you would hardly ever clog.
But there are a lot of lousy, low volume toilets. Do research before buying.
See how I used lousy, not the C word there.

What I do not get is I thought there were only a few toilet manufacturers. Toto, American Standard and Kohler (I think). (Note that I mean actual manufacturers, not brands)

Would they really make lousy toilets that clog if they invented ones that do not?

If they did that would be…lousy of them.

That is a very sketchy realm of reality. Price versus actual cost of manufacture plus markup. At a rough guess, I think casting a ceramic piece of complexity of a toilet bowel has been perfected for some time now. Metal casting has come such a long way, and is a later science.
The added expense of glazing the entire exit path does not seem a large percentage of cost. Once you have perfected a good flow path, the expense may only be a small amount of extra material per unit. Maybe even less material.
When the same manufacturer has multiple designs in the same basic product, the pricing becomes a real psychological game. The percentage cost of various things to differentiate their base, mid, deluxe items, often varies wildly in the final price percentage difference.
There is an issue of mass selling to cheap contractors at a low price. Make a lousy toilet for them but really cheap. ( did not use the S word ) Then offer a good one to good contractors at a good price. Then, make a fancy but basically as good as your good one to the next level market. It just has cooler looks and shiny bits.
So a toilet that is actually subpar. Then one that works well in several tiers of coolness and price.
I suspect the majority of toilets are sold to big contractors building housing developments or apartments. So the cheap ass contractors will have many folks plunging their clogs, but they shaved off a bit on each toilet. The good contractors will have satisfied customers flushing their cares away, but maybe lost a bit on cost, gained on reputation. Then there will be the more gold plated situations.

I forgot to mention:

I think Toto claims it improved the siphon effect that toilets have. Kinda like a suction that pulls things through.

Again, I have no idea how much is truth and how much is marketing.

With low volume, siphon effect does matter more. If it is visible you can see an on it’s side S shape under the bowl. At the start of the S the water coming from the bowl and down from the tank is pushing the waste into the S. As the waste courses through the S it reaches the high point of the second bend, than goes down towards the floor. In this section, at the end of the flush there is no more water coming in. So the outgoing water column creates some siphon action to drag the contents fully out. For maximum effect you have a lot of calculations and testing to figure out the maximum force to get it over that last S hump without just burping and back flowing that last bunch of stuff back into the lower S section. It does take some science/art to perfect.

Soft close lids with lights are the cat’s meow.

It’s like anything else; when there are some kind of performance-impacting regulations imposed on a product, it takes the manufacturers a while to work out the kinks and have the products working adequately again.

Take dishwashers. They finally took the phosphates out of dishwasher detergents in about 2010, and it took manufacturers several years to really figure out both how to manufacture effective phosphate-free detergents AND dishwashers to use that detergent. But if you bought one in say… 2010 or 2011, chances are you got a fairly cruddy dishwasher relative to getting one in say… 2015. In this situation, the detergent manufacturers leaned into enzymes pretty hard, and dishwasher manufacturers changed up the cycle times to be considerably longer, among other things.

Toilets are the same way; the old ones relied on having a lot of water flowing through them. Then the legislation restricting water usage was passed, and now the design became MUCH more critical- stuff that wasn’t important at 6 gallons per flush is suddenly front and center design-wise at 1.28 GPF. So they’ve worked on that, and the newer, non-budget models are just as good as any of the old ones ever were, and use 1/6 the water. It took a while for those to be developed, so for a good while there were really terrible low-flow toilets being installed, and a lot of those are still in service, giving the whole concept a bad name.

I have seen many posts in GQ/GF about clogged toilets and I find it strange. In my 60 plus years of using flush toilets in the UK I have never been aware of a clogged toilet that wasn’t caused by someone putting stuff down there that it wasn’t designed for.

My conclusion is that either US toilets are poorly designed and installed, or Americans create much larger turds.

The rule here is that "no flushing device installed for use with a WC pan shall give a single flush exceeding 6 litres (1.58 US gallons) and waste pipes for toilets and main connection to underground sewage systems from the house to the street have to be at least 110mm (4.33 inches). How does that compare to US codes?

In the early 1990s, a new law (aimed at water conservation) limited new toilets to using a volume of no more than 1.6 gallons per flush – so, not dissimilar to your code.

But, prior to that, a lot of toilets used a lot more water, and they could get away with reasonably inefficient designs, just because they were pushing so much water through the bowl. The first generation of “low flow” toilets in the U.S. often didn’t include some of the design improvements discussed upthread, and thus, led to much frustration from homeowners, as those toilets lacked much power in their water flow, sometimes required multiple flushes to clear the bowl, and clogged more often.


My office building has a common bathroom on each floor (as I expect all do).

I have had the experience of being in a stall next to someone else and I can hear them using the toilet paper roll. And it is obvious they are using a LOT.

It is hard to sit in judgement about how much TP is too much TP but at some point…it is too much TP. And believe me…this person was using too much TP. To the point of being comical except it was bizarre. I truly mean ridiculous. It went on and on…

And this happened more than once.

I’ve walked into a stall seeing clogged toilets with waaaaay too much TP in them so clearly it is not just one person (at least I hope not). I don’t get it. Even if you (general “you”) have a really bad time on the pot do a flush part way through. Not difficult or an imposition.

Maybe this is a US only thing but I would guess not.

Don’t eat out at Mexican restaurants, :taco:, eh?

I was going to hypothesize about this being a difference, too. I have no idea if Americans actually use more toilet paper, on a per-flush basis, than the British do, nor if thicker/softer toilet paper is as popular in England as it is here, but I think I wouldn’t be surprised if it’s a factor in toilet clogs here.

It has been a while, but my experience with standard issue British toilet paper has been it is more like 120 grit sandpaper and so does not encourage using any more than absolutely necessary, and that gingerly

The answer to what makes one toilet perform better than another is…Science.

I’m in the market for a Kohler Numi.

It has a motion-activated and heated seat, foot warmer, illuminated panels, air filter and it plays your favorite tunes.*

It’s supposed to flush too.

*“Constipation Blues”, perhaps. And in England, “God Save The Queen”.

Wow. And I thought this was joke: