Why can't I buy a siphonic toilet in the UK?

March 1, 2020 3:46 AM

I grew up in the US but have lived in the UK for nearly a decade and a half, now. When asked what the UK does badly, I always say "toilets". The "washdown" design is smelly, messy, and the only advantage over the siphonic design used in the rest of the world is that it doesn't clog as easily. But both designs use the standard 3L/6L flush, so why can't I buy a siphonic toilet in the UK?

Manufacturers who offer both siphonic and washdown models in the US offer only washdown and shelf (if you don't know, you really don't want to) models here. When I pressed suppliers on this, they claimed that siphonic designs "don't meet the byelaws". Pressing further, they claimed they "use too much water" and one even linked me to a forum thread where a bunch of plumbers were actually corrected after making this claim.

I have come to accept that I will still end up with a messy european-design toilet that requires me to use a brush to do half the work of flushing each time. But I just want to know what is it that makes these fixtures not suitable for the UK market!

posted by rum-soaked space hobo to Home & Garden (14 answers total)

It's much more likely to be a cultural thing. People in the UK are familiar with washdown toilets, and don't expect to encounter siphonic ones. Plumbers don't fit them because there's little demand for them, and having two different systems in use just adds unnecessary complication.

To replace something in such common use, you need to offer a product that's clearly better in an overall sense. These two toilet design each have pros and cons, so there's nothing to drive widespread replacement. As someone used to one type, you're always going to see what's wrong with the other; you're less likely to notice the things that are slightly better.

As well as being less likely to clog, a washdown toilet doesn't project so far from the wall, so it's more suited to our smaller bathrooms.

It's very unusual to need to use a brush every time. Maybe you just have a toilet with a bad design. Limescale build-up can also turn the smooth ceramic rough, which can cause problems. A good descaler such as Kilrock can help with that. And there does seem to be a new coating (it was widely reported last year) that has the potential to make toilet bowls super-slippery and dirt-resistant. I didn't see it available when I last shopped for a toilet, though.
posted by pipeski at 4:37 AM on March 1, 2020 [5 favorites]

Response by poster: I hear people claim they don't have to use the brush much, but it's a bit shocking to walk into an office loo and see signs everywhere scolding people for not using it. This simply. isn't. a. problem. elsewhere.

But also simply having the waste hang out in the open air pre-flush is revolting. It's like a halfway step between German/Dutch-style shelf models and a proper siphonic toilet.

I am going to try a more modern rimless design that seems to aim the jets a bit more completely, but I'm just curious why suppliers say siphonic models violate the byelaws.
posted by rum-soaked space hobo at 5:15 AM on March 1, 2020

I'm a bit baffled by your descriptions of UK toilets. As well as rarely having to use the brush, I've never seen a toilet in the UK that involved stuff being in the open air pre-flush, it just drops down into the water. That's true to the point that when I was in Eastern Europe/Russia it took some getting used to that there was this little dry platform that stuff just sat on in open air before you flushed. I'd literally never seen that before or since, in a lifetime of living in the UK. (She asks with trepidation...) Where is it sitting if not in the water? Maybe shuffle back a bit so that it actually drops into the water? Even when people do have to use a brush, I feel like that's because it's hit the sides on the way down into the water, not because it's settled somewhere on a kind of dry perch (Sorry, this doesn't answer your question about why we don't have siphonic toilets, I'm just kind of curious that your description doesn't chime with any toilet I've seen in the UK!)
posted by penguin pie at 6:28 AM on March 1, 2020 [5 favorites]

Siphonic verses washdown.

It's may be they just don't meet (what we'd call here) code (IE:building regulations) as zany as that sounds. Code/Byelaws/laws in general aren't always 100% logic based. Someone (or a group of someones) who are writing the regulations have a preference (however logical or irrational) and encapsulate that into a regulation. After a few decades that is just the way it is and woe betide anyone who proposes a change. Often it is started or perpetuated as a form of regulatory capture (at one time maybe only British companies made the wash down style but siphonic style was made off shore or there were patent issues). And so you end up with a situation where something millions of people use elsewhere is considered unsuitable.

Examples of this abound in the Electrical world. Things that are perfectly legal in the USA are illegal in Canada and vice versa and our systems are integrated and essentially the same. EG: Canadian plastic boxes have ground straps but American boxes don't; America doesn't require a service barrier but they also are allowed 6! breakers in a main disconnect where Canada requires just a single handle. There are hundreds of these little difference. See also where our electric kettles suck and it is essentially illegal to use British kettles even if one was motivated to supply the necessary power because the British unit isn't listed in Canada and cutting the cord end off to install a Canadian version would violate the listing anyways.

Also the Americans are stuck with Phillips screws instead of the obviously superior Robertson variety.
posted by Mitheral at 6:48 AM on March 1, 2020 [4 favorites]

The 2 advantages of UK (and, IME, almost all the rest of Europe)-style toilets:

1. No splashback
2. Very rare that it clogs*

*I did have one clog a few years back, I suspect because a guest disposed of a pad in it, and the other advantage that I did not find out in time is that the connecting pipe between the ceramic and the foul water drain is made from flexible enough PVC that you can squeeze it from the outside to dislodge a blockage.
posted by ambrosen at 6:49 AM on March 1, 2020 [3 favorites]

Best answer: The trapway on washdown toilets is almost twice the size of a siphonic design. It is in theory possible to connect a siphonic toilet to a washdown trapway, but you would need some kind of converter joint. So then you either need to raise the whole toilet by a few inches to make space for that, or cut down the trapway pipe to make room. If you go the latter route, that is likely to involve lifting the floor to gain access and may also make it difficult to revert back to a washdown toilet in the future without replacing the whole trapway which is likely to involve some really major expense.
posted by Lanark at 6:56 AM on March 1, 2020 [3 favorites]

Best answer: Lanark, UK toilets have a waste pipe that exits horizontally a few inches above the floor, and is usually plumbed across to a vertical soil pipe. They're quite different from US toilets, which drain below the floor.
posted by pipeski at 7:35 AM on March 1, 2020 [3 favorites]

^ well that just makes the plumbing connections even harder!
posted by Lanark at 8:50 AM on March 1, 2020 [2 favorites]

Best answer: and shelf (if you don't know, you really don't want to)

But if you do want to know, Scott Anderson's German Toilets page is still available.
posted by Rash at 9:20 AM on March 1, 2020 [10 favorites]

Re the need to use the brush. If your posture on the loo is one where you are leaning forward. you have angled your colon towards the back wall of the bowl. If there is gas pushing the poo out, this more or less guarantees the poo impacts the rear wall - cue the brush. Sitting upright, spine vertical, reduces this (unless you have the gas/loose poo combo).
posted by GeeEmm at 12:55 PM on March 1, 2020 [1 favorite]

Austrian toilets as well as German have, or used to have, the "shelf". My beloved but sadly departed Grandmother had a stellar example of this in her house. Oddly, it was sequestered in its own room, away from that other Euro item, the bidet. Presumably this was to keep the, um, exceptional odors contained.

I do not have an answer to your question, other than such toilets do appear to be configured differently to the point that installing a North American version would cause problems. They certainly wouldn't have fit in my Grandmother's designated toilet closet.
posted by Crystal Fox at 11:19 PM on March 1, 2020

Response by poster: The actual pool of water on UK toilets is tiny compared to US ones, so yes you need to be perched precisely and have everything go predictably to hit it. And yes, we're in a hard water area (London), so stuff that hits the sides just sticks there against a medium of limescale. This is why I consider these things to be effectively the worst of both worlds between shelf and siphonic: when you do nail the bullseye, you get an extremely vertical "splashback".

The other problem is that the jets of water aren't always aimed completely. Often two jets will splash to the sides, and one will trickle down the back and then jet over it to aim at the hole. This is one reason we're always doing the rest of the toilet's job with a brush at home, work, and in public places.

I've resolved that for my upcoming bathroom renovation I most likely will settle on a modern "rimless" design that creates a proper vortex, and which has a slightly larger-than-average water surface area.

Thank you for the explanation about the trapway geometry. I think that makes the most sense for why they wouldn't be sold at all, here.
posted by rum-soaked space hobo at 3:25 AM on March 2, 2020

@GeeEmm -- you are right about a leaning forward posture making the brush required each time. However it is much healthier and more effective for your body to lean forward. "squatty potty" made a video about it: https://www.youtube.com/watch?v=YbYWhdLO43Q.
posted by richb at 7:13 AM on March 2, 2020 [2 favorites]

London water is super hard, so you may find a different design would still be similarly hard to clean.
posted by Lanark at 10:15 AM on March 2, 2020 [1 favorite]