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Splash-free urinals (2025) (oup.com)
138 points by u1hcw9nx 2 hours ago | hide | past | favorite | 69 comments
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Worth noting that this study was partially funded by the university of Waterloo

Nominative determinism.

Nice domain name too.

And is on PNAS Nexus.

Now I have to go.

Ig nobel prizes were just a few days ago:

https://improbable.com/ig/winners/#ig2026

Edit: The splash free urinal was the winner for physics!

I once joked that these do more for science than Nobel prizes. Now I don't think it's a joke: "wacky but interesting" awards are more important for the advancement of science than "everyone agrees this these people should be even more famous" awards.


Global sustainability and accessibility seems a bit grandiose lol. It’s just a urinal after all. That being said, it’s been 4 years since Waterloo first determined this and it’s still unavailable to purchase. I’ve been patiently waiting for one to install in my shop but it seems like it’s not all that important for the globe if it’s still unavailable 4 years later.

Things we take for granted, like washing hands, were pivotal in reducing illness in hospitals.

If 50% of the population walk out of a public bathroom without tracking urine on their feet or anything else that touched the floor and custodians have 99% less bodily fluids to deal with, that seems like positive progress. Maybe it will move the needle in ways that are unexpected.


I would love to see some Nautilus style urinals because--as a self-interested adult--splashback also hits me if the angle is bad enough. Sometimes I even use the stalls to avoid those porcelain tricksters entirely.

Same attitude that prevents the urinal manufacturers from switching I reckon

I remember being annoyed by splash back in sixth grade. I mocked up an alternative design (essentially, a urinal that tilted away from you), and emailed some friends. They never responded, and I never followed up.

Looking back I feel sad - that's the kind of curiosity to nurture in a kid. But peers are rarely the best group, it would've been better to tell my parents or the right kind of teacher. My friends also could've said something: " I don't know what to do about this but you should tell ms blah blah blah", in a serious way not mocking way.

I'm glad someone else has finally looked at this sticky situation


You would have been an excellent splash sputter scientist.

> I'm glad someone else has finally looked at this sticky situation

Wait ... your splash variants are sticky???


I mean you're sad about a hypothetical. Why not consider the alternative where even your parents and teachers will probably not care because who wants to hear about a splash free uniral design from a kid in sixth grade. Like if some kid walked up to me with that, I would ignore them too sorry.

Design through physics and differential equations.

This paper is Ig® Nobel Physics Prize Winner 2026 https://improbable.com/ig/winners/


The recent introduction, in the UK at least, of splash-back reducing urinal … mats (?) has basically solved the problem in my opinion. They’re a disposable (but not single use…) plastic freshening insert with loads of short rubber strands, closely packed.

You can pee on one of these mats and the stream almost aerates itself on impact and you get basically no splashback, I guess with a similar mechanism to how an aerating tap produces a stream of water that doesn’t splash off whatever it hits.


Yes this is the best solution I've seen. And every male pretty quickly figures out that the angle of the stream greatly affects splashback. Seems rather wasteful to spend money on this study for a solved/non-problem.

We've had those in the US for several years now, and they work really well.

I did encounter an upside-down one yesterday. That was... counterproductive.


The worst urinal which I used was in Brussels about 15 years ago, and with that "splash-back reducing" mat. And it covered every part of the inner wall of the urinal. The mat caused the exact opposite of what it was supposed to do. It made it worse, and I had to wash my shorts, because it started to smell disgusting the next day.

Sometimes i am using an urinal and i feel like no engineers were involved in the design. Glad to see someone is actually approaching this with proper science.

There is more to it than the splashback tho. Sometimes it seems that the surfaces that already have splashes on them are not angled properly to lead the water to the drain. This seems to create need to have sharp edge/lip rather than round one, which might be tricky to make resilient in porcelain. But the rounded lip certainly allows for droplet flow towards the user rather than the drain hole.


My pet peeve about urinals has to do with the way the separating walls are usually installed. It's systematically too low, as if their goal was to prevent splashing between each station instead of their role of visual privacy.

Go visit an older stadium in the USA. Either no separating walls, or just a trough where you stand shoulder-to-shoulder with the people on your left and right. Eyes forward.

> as if their goal was to prevent splashing between each station

Frankly, this is more important to me. I’m not looking around, and if someone else does, that’s their problem.


I very rarely see separating walls in the UK. Are they common in your country?

No amount of engineering can solve the problem that no matter how much you jiggle, you shake, or you dance, the very last drop always falls in your pants.

Even if a urinal doesn't splash, there's usually (always?) a decent amount of fine droplets that eject out from the stream since the flow is rather turbulent. On top of that, the fleshy opening is never completely stable.

What we really need is laminar flow!


A custom 3D-printed user-matched disposable nozzle, perhaps? One could carry a handful in his pocket and don before the act.

> High-speed images of splash events generated by flow from an anatomically accurate nozzle

They had some fun writing this.


Just aim at the sweet spot where your stream smoothly swirls into the plughole. No spray, minimal sound. Most toilets and all urinals have this spot you can hit. In Amsterdam airport they even mark it for you with a crosshairs!

My stream doesn't have constant pressure throughout the process ;-)

I really like the inverted version, where it's almost guaranteed to splash yourself as a deterrent.

There are historical examples of this in some alleys in central London (https://www.exploringgb.co.uk/blog/9th-century-urine-deflect...).

I remember being unpleasantly surprised by one after a particularly heavy New Year's as a student.


European closets have the same issue. Indian closets does not. Actually Indian closets are superior in every way if you have good knees...

Traditional urinals [1] are very effective. As are the steel variants [2]. The latter tend to become very grim over time.

[1]: https://www.hlwashrooms.co.uk/healey--lord-niagara-urinals--...

[2]: https://acornthorn.co.uk/urinals-wcs-cubicles/urinals/ur068-...


> droplets which travel back onto the floor and user

I suppose this disproves Tufte's "There are only two industries that call their customers 'users': illegal drugs and software."


They have had these in Japan for a while now it feels like.

Nice, but does it takes into account that some droplets are directly issued from the hose itself ? Not to mention the double stream problem ^u^ Cool paper nonetheless.

Direct link to the designs (c and d, with d being practical). Great paper honestly.

https://academic.oup.com/view-large/figure/512223725/pgaf087...


I love that La Fontaine is named in tribute to Marcel Duchamp[0], even if calling a splash-free urinal a fountain would seem a bit confusing on the surface.

[0] https://en.wikipedia.org/wiki/Fountain_(Duchamp)


That takes all the fun out of using public toilets.

One of the more interesting scientific studies was the behavioural change of when you put down the image of a fly on an urinal. These flies are suddenly targeted by strong streams as if there is no tomorrow ...


It’s not much help if the aim is off

Install the urin-no next to it to help "improve" the aim.

The secret to splash free male urination is..sitting down.

In a public toilet? Not happening. Back to square one.

Always carry wipes?

I fail to understand why anyone is scared to place their bare thighs on a public toilet seat. Do you have open wounds on your legs?

Can't speak for everyone but in my experience using public toilets (predominantly UK, pubs and train stations):

* there's not always a properly functioning seat / seat at all

* the seat is not always dry

* the cubicles do not always have a functioning lock

* the bowl is not always 'clear'...for reasons probably best left unexplored, people seem to choose public toilets as a place to carry out the most incomprehensible and unimaginable of all bowel movements. I've been greeted with bowls that let's just say would be benefit being assessed by a trained professional

Public toilets are also often pretty grim places in general due to the smells, sounds and general lack of hygiene/cleanliness.

All that said...IF the toilets look in decent repair I personally will use the cubicle and sit down, but it's probably less than 30% of toilets that feel like that's an option.

Also just to say I am someone who always sits to pee whenever at home/in a person's home and i'm not someone who anyone would ever call a germaphobe, so I do generally choose to sit rather than stand.


The gents loo at a non-posh UK pub is about the lowest you can go in the western hemisphere.

I don’t care if my bare thighs were coated in the most potent prophylaxis known to man, I am not sitting on another man’s piss and or shit.

Yeah, the issue is that it takes one disgusting degenerate who doesn't know how to use a toilet and pisses all over the seat or worse.

I'm purposefully not calling these people uneducated, because I routinely encounter it in an environment full of highly paid and educated people with Stanford, Harvard, Princeton, etc... kind of education. These people come from money, earn money and are supposedly educated. And yet, they will happily piss all over the toilet seat and not even bother to clean it.

Shows also that money doesn't buy class.


Agreed it's 100% not an education/money/class thing. I moved into a larger office, high tech company, and the number of times people need to be told not to leave the toilet in a state or to take their rubbish out of meeting rooms when they leave is eye opening. A large number of people from all backgrounds are just animals.

In the line of thinking of educated toilet shitters - why clean up after oneself when there is, from childhood, always some underpaid person of color that does the cleanup for you?

a) sitting on piss

b) sitting on a seat you just wiped piss off

c) piss on the floor which will get on your trousers if you sit


At home? 100%. Out in the world? Very much depends.

I was just in a stall where the inside of door had a pictogram forbidding users from standing on the edge of the bowl and squatting. I assume this might be for visitors from countries where squatting is common.

Point being, you just never know what random members of the public will do with a door to hide behind.


Even women won't consistently sit down on public toilets

This reminded me of some scenes in the videogame Dispatch [1]

[1] : https://static.wikia.nocookie.net/dispatch/images/c/ca/Dispa...


it includes an anti-urination idea for outdoors, which may be worth noting.

Somebody tell Larry David about this

No defecation allowed

Sustainability?

What resource will we run out of if we continue to piss in traditional urinals?

Has bullshit marketing terms invaded scientific papers now as well?


There was a trend for a while for waterless/flushless urinals to save water. Though I would guess those have higher cleaning costs so not sure how that worked out in the end.

not so long ago it was very fashionable to include DEI/ESG/etc lip service in those things, regardless of whether it made sense. for example, I've read a study comparing leather tanning compounds and it had a completely out of place paragraph babbling about climate change. the author wasn't even American, it's a global cargo cult.

Water and chemicals spent on cleaning. Less splash means less cleaning.


Honestly not a bad idea

The previous design was piss-poor

Piss-rich?

Just pee in the sink

> At Amsterdam’s Schiphol airport, the use of fly stickers to change aiming behavior resulted in a reportedly 50–80% reduction (not elimination) in splashback observed and an 8% reduction in cleaning costs

It's surprising it's that high (8%). I would imagine it takes as long to mop a floor that has pee droplets or mop a floor that doesn’t. And someone still needs to mop the bathroom floor anyway and go into the bathroom anyway. Unless you pay the cleaners by hour instead of having them on payroll, monetarily I don't see the difference.

I expect cleaning costs to be dominated by the long tail, ie every bathroom cleanup job being the same except for the odd time when someone threw up on the floor or sprayed poop on the walls or what have you.

Still nice to not get pee on yourself though, that part is good.


TLDR: The "Cornucopia" has the least amount of splashback, however the "Nautilus" is the recommendation of choice, to accommodate ease of cleaning and variations in the height of the user.

https://academic.oup.com/pnasnexus/article/4/4/pgaf087/80987...




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