Does Water Swirl the Other Way in the Southern Hemisphere?

The definitive answer about the direction water swirls in two hemispheres
Sync the videos yourself: http://toiletswirl.com

For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time.

The idea that water going down a drain or flushed down a toilet swirls in opposite directions in the Northern and Southern Hemispheres has a long history. But few have ever done the experiment. Destin from Smarter Every Day and I performed identical experiments in the Northern and Southern hemispheres. What we found is the direction of water swirl in a toilet, sink, or bathtub is determined by other sources of angular momentum. However if the body of water is big enough, e.g. a kiddy pool, and left still for long enough (at least 24 hours), then the Coriolis effect is observable with water swirling counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere.

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Gordon McGladdery did all of the sound design for the video. We used two songs from other artists (licensed of course). Derek split the first one up so it fades from video to video, and Gordon split the instruments up on the second one. There are violins on one video and percussion on the other for example. It's really neat.

The neat earth animation at the beginning and the synchronizing timer was made by http://eisenfeuer.com/. He also made still images of the earth from the top and the bottom.

Thanks to Vanessa for filming in Sydney: http://youtube.com/braincraftvideo


There was a study performed at MIT years ago (http://web.mit.edu/hml/ncfmf/09VOR.pdf) that explained the physics involved. We repeated some of these demonstrations, but on opposite sides of the globe…and in a way that can be easily understood.
This site is a great resource on the Coriolis effect and ways people have gotten it wrong:

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Автор Andrew VanCamp ( назад)
but what about near the equator? hmmmmmmmm? you ever think about that?

Автор MomoPiano ( назад)

Автор Dzon Vejn ( назад)

Автор Kevin Klatman ( назад)
My dairy queen ice creem swirled the same way in US and australia though.

Автор Findivist ( назад)
not bad, but it would be good to repeat same experiment a few times to see if there is any consistency.

Автор W2S 2 ( назад)
I ' m just asking : What causes the water going down a drain to swirl clockwise in the northern hemisphere and counter clockwise in the southern hemisphere ? Plz answer

Автор Colin McPhail ( назад)
I love how they had to make this huge experiment to prove that the Coriolis Effect was real, when all they had to do was talk to a commercial jet pilot or look at a hurricane.

Автор Intelligent Gaming Agar ( назад)
Legends have it that if you are exactly on the equator, water will come out of the drain instead of water going in the drain.

Автор Derrick CFT ( назад)
I just want to say that I really like your videos. Keep em coming and thank you

Автор BoxySama ( назад)
this animation help me understand the Coriolis effect 100%

Автор Kargadan ( назад)
I am not buying this. It cannot be the effect of earth's rotation. specially on such a tiny diameter pool!! it is more than negligible. to prove such a thing you would need a very big pool (like the one shown on the cartoon). there must be other factors at play here that we either don't know of, or that we are not considering(gravity curving space/time or etc..). imagine an ant being on top of a globe, from the ant's perspective the globe would look flat cause it is so tiny that the curviture is minuscule/negligible. there is not way that earth's rotation has such an effect on such a small scale. if you had a pool the size of what you showed on the cartoon it would make a lot more sense.

Автор pratik : } ( назад)
hey bro,i liked your most of the videos. keep it up:)

Автор MomoPiano ( назад)
Wow do you know our language?? This is so fantastic!

Автор Manish Jones ( назад)
The things we do for science ! Derek ,for Science...

Автор Nick Robinson ( назад)
What happens when the center of the pool is on the equator?

Автор Stephan K. ( назад)
was that a 5σ experiment?

Автор TiggrrZ ( назад)
I always laugh at this, water doesn't really swirl at all in the UK.

Автор HeLaXeRN HeLVeT ( назад)
counter clock wise bottom of the sphere and clockwise on the top,tornadoes goes the opposed way of the sphere because air its less dence than water?

Автор Vgamer 3802 ( назад)
then what happens in the equator?

Автор Berfras ( назад)
I believe that the experiment has some small flaws that make the results inconclusive. For example, it looks like adding the dye during the experiment created noticeable water waves. However, it's a nice video. :)

Автор 444mrjimmy ( назад)
thank you so much for uploading this Derek, I did manage to get the videos to sink on the very first try but haven't been able to do it sins

Автор Aryaman Mishra ( назад)
what if they were perfectly on equater

Автор Mark TNS ( назад)
what happens when you put the pool right on a pole?

Автор Benther ( назад)
Yeah Dustin.. we knew the Coriolis effect is real....

Автор Martin Ducharme ( назад)
That a really cool experiment, I hope you'll do more cooperative videos like that.

Автор Niklas Kaplan ( назад)
What happens if it's on the equator? :P

Автор Ibrar Khan ( назад)
dear sir have you an email ,i want to contact with you

Автор Edward Ramirez ( назад)
Insufficient sample size! Awesome none the less!

Автор stereosphere ( назад)
I think water swirls the same direction in both hemispheres. The problem is that the Australians are standing on their heads looking at the bottom of the swirl.

Автор Jen L ( назад)
this is ... A M A Z I N G

Автор David Niedbala ( назад)
What happens if a hurricane crosses the equator? will it come to a halt and start spinning the other way?

Автор Chris Reich ( назад)
Wow, I didn't expect to ignite controversy. Really, my whole point is to encourage people to think scientifically and question results. That doesn't mean we never accept proof, but we should think deeper than we normally do. Science isn't a debate of opinions, it's a quest for fact. When an experiment is conducted, we want to look for flaws that could be tainting the results.
I love physics and encourage people to think about these things. When an experiment is conducted, we should look for potential flaws. As we know, in the case of the directional flow of drains, starting conditions can make the swirl go in either direction in either hemisphere. Knowing that, we should be especially diligent about starting conditions. Real scientific discussion is valuable and can be a lot of fun if we skip the vitriol and enjoy the topic.

Автор Só mais um aglomerado de células pensante ( назад)
what happens in the equator? does It moves in anticlock direction or in the clock direction?

Автор Yangven ( назад)
But... what if its on the equator?

Автор ThatGuyMike ( назад)
People claim to see this a lot, but most plugs these days have designs that affect the waters directional vortex.

And the video is anyone going as hell. They were not meant to be put together like this.
1 muted and 1 with audio maybe, but it gets annoying to hear the same thing twice.

Автор Super-patfan39 ( назад)
Wow.......... cool

Автор Aaron Osher ( назад)
By far my favorite collaboration on YouTube ever.

Автор Lizard Mods ( назад)
I've already seen both videos but I never realized how much work you guys put into it crazy!!!

Автор Shakeel Alam ( назад)
i think this all due to "Coriolis effect". not only the ocean water but also the air current swirl through the same phenomenon. is this so?

Автор Adnan IB ( назад)
Why re upload old video?

Автор kevin ( назад)
science channels on youtube are by far my favorite

Автор andrei oprea ( назад)
this is not a ultrawide video.. them black bars on a 21:9 monitor thow

Автор Tristen Hernandez ( назад)
Any idea where i can get a list of book siggestions from Veritasium?

Автор Skope Theo ( назад)
But what if you try this experiment in the equator?Will the water not rotate at all?

Автор fudgesauce ( назад)
I remember watching this video two years ago. I didn't believe the conclusion then, and I don't believe it now. You took one data point, essentially. Coriolis effects manifest on the very large scale, not over the span of a meter or two.

Автор Sy Fontenot ( назад)
Will a cyclone never form at the equator because of this? What if a tornado from the north enters the south? Will it die or will such a thing never happen?

Автор Billy Overton ( назад)
please spam flat earthers with this, I want their explanation.

Автор Jone Robbins ( назад)
I thought that is why vehicles manufactured in Southern hemisphere bolts and screws go the opposite way.

Автор Wood By Wright ( назад)
still one of my all time favorite colabs!

Автор Tom Tom ( назад)
That was very lazy... nice to rewatch it though... and I am still annoyed at the definitive conclusion based on one experiment.

Автор Eclipse007 ( назад)
If they have just said that the "experiment" was just a demonstration of the real experiment done years back, then the people saying that this is not scientific would have been silent since... but this is the Internet, i dunno what you guys want.

P.S. famlit

Автор Granolees ( назад)
Yeah but the earth is flat sooo....this is fake

Автор J Z Drake ( назад)
Quick answer to the title: only because of construction.

Автор Mint Slice ( назад)

Автор Sergey K ( назад)
Probability of the same result accruing by random chance is 1:4. You could repeat the experiment on a non spinning planet and 25% of the time you would get this results.
So is it a "proof"?
PS great explanation and well done for trying.

Автор CNCmachiningisfun ( назад)
And with that, the flat earth 'theory' goes down the drain :) .

Автор No Gandalf ( назад)
Aside from all the other variables others have mentioned a sample of one experiment provides evidence but not confidence (let alone "proof"). If this arrangement does indeed demonstrate measurable Coriolis effect I'd be interested to know how small the pond must become before the effect vanishes into noise.

Автор Dark Horse ( назад)
Actually you can see it in a sink now, bathtub and toilet. 🙄 The only questionable test conclusion would be the toilet which a person would have to take into consideration did the manufacturer adjust how the water entering the toilet would actually flow or enter during the moment of flushing. For instance whether slots were cut a certain shape in the toilet bowl which would account for the rotational and directional created spin of the water. The calculation for water pressure also comes into play during such a test as the force then forces the water to flush the toilet.

Автор VVindowZ ( назад)
sorry for the CAPSLOCK :D


Автор Monkeysrock ( назад)
That was really well done.

Автор Sly Rocko ( назад)
What if you drain it exactly at the equator or at least as close as possible?

Автор Nancy Lee Fransen ( назад)
I have been wanting to see these vids this way since I first watched consecutively. THANK YOU!!!

Автор Sean Haggard ( назад)
so...why does water swirl at all? I don't mean to explain the Coriolis effect, I mean why does water draining form a a vortex.

Автор Something Wrong ( назад)
so, how it works on the equator ?

Автор justsomeguy ( назад)
Sci show my ass!

Автор GlowBox ( назад)
I love this

Автор Nourredine Kebaili ( назад)
One experiment can not make a rule, you have to do it many times and make some statistical conclusions. You have to be able to predict the direction at least in the equator!

Автор Saeed Zafar ( назад)
Well that is about Pole and Hemisphere, What about Equator itself?

Автор Slick1G3 ( назад)
all rivers on one side of the earth flow north to south ..the opposite flows south to north

Автор Philip Freeman ( назад)
I do wish you had repeated the experiment a few times. It makes sense that this effect could be real under such controlled conditions, but there is also a 1/4 chance of getting this result due to random chance. A couple of repeats would have made for a much stronger result. As it is we don't really know if this effect is truly observable.

Автор Tim Barton ( назад)
toilets are bad examples.

Автор Crystal Smith ( назад)
Also, the pump generators need to be the exact same pump as the magnetics within the generator will determine which way the blade spins in the generator. If the same and the flow still is opposite then I believe it has more to do with the magnetism involved with the Hall currents and the "Magnetosphere'' , electrical currents in the air, than the water, which gives the motors it's magnetics. Not sure on that one exactly. There are more things to consider in this than just filling up pools and pumping out the water with pumps. But that was enough for you to make a You Tube vid and get clicks and 'prove' something that doesn't seem to be very scientific proof. Hats off to you for having the gumption to make vids for You Tube. Good luck!

Автор Crystal Smith ( назад)
It appears to me that the spinning earth models you show are having the Earth spin clockwise in one and counter clockwise on the other. As if it would appear to spin in the opposite direction from the vantage point of the which 'pole' one is observing. That WOULD NOT be the case. Also, which way the water flows would also be proportionate to which way the HOSE is falling, I.e., more left or more right of the suction end of the hose in the pool, and also any bumps or hills on the ground. This is not any solid proof that "holds water". ;) the 'experiment' needs more controls on it as in a lab, to be "scientifically" sound. And you called this 'science' or just a layman's experiment? The toilet one was more right since flooring is USUALLY, leveled out on building and laying the floor. This in my haughty opinion, not so humble, as most commenters never are as I see, is a FAIL of PROOF of anything. But... Low analyzers will buy it in a heart beat!

Автор Wi1dcard86 ( назад)
There's a place in Ecuador called the "la mitad del mundo" Which translates to "the middle of the world". It's a park that is placed at exactly 0 degrees latitude which is marked by a line splitting the park into the north side and the south side. For scientific purposes I went in and flushed the toilets on both sides...despite what this video said about interfering angular momentums from toilets, I guess I got lucky and saw swirls going counterclockwise and clockwise from the north and south respectively. Can confirm legitness.

Автор Darrell and Sondra Holden ( назад)
Hmmm, let's see, you might want to also talk to professionals who have worked with water systems in both hemispheres - there is no doubt - it DOES swirl in opposite directions. We know, we've lived in both hemispheres!

Автор Kevin De Le Ree ( назад)
So if the earth didn't spin at all, would we have tornado's?

Автор Randall Kelley ( назад)
OMG, like no way dudes. You just burst my bubble, dang...just to complicated...

Автор Andrew Miller ( назад)
wait what dose water do exactley at the equator?

Автор Obertone3 ( назад)
The Sci show does not do it`s own science. Circumcise that

Автор ShadowCatGambit ( назад)
Does the gravitational pull from the moon effect the swirl in any way, and what would happen if these experiments were done directly on the north pole, south pole, and equator?

Автор Brian ( назад)
would have been cool if you'd thought to synchronize the experiments in real time as you were doing them. not for any reason. just for fun

Автор Mac ( назад)
I live in huntsville

Автор tupakveli ( назад)
cool, so the right hand rule is useful for something other than annoying the f**k out of me in class :D

Автор Marlon James Dimailig ( назад)
The snyncronizing part was satisfying

Автор FMJPatriot ( назад)
"Anti-clockwise"? 🤔

Автор Randi Rain ( назад)
Scientific America disagrees with you...


Автор Brian Kelly ( назад)
Wait a minute - the Aussie said it's a 5 foot wide pool and the guy from Alabama said one and a half meters... I need a drink.

Автор DBXD ( назад)
very cool!

Автор sweggy mcsweg ( назад)
What would happen if you repeated this experiment at the equator?!?!

Автор JOHN KRANE ( назад)
So much for flat earth

Автор Christian Battestin ( назад)
Simpsons did it!

Автор Philippe Marseille ( назад)
These are the videos that got me to become a subscriber to both you channels. Keep up the great work guys, you both are, really, both, part of the best channels on Youtube!

Автор Nicholas Fanelli Hugueney ( назад)
Awesome work, guys!!
I love both of your channels.

Автор blue frost ( назад)

Автор Ovie Imoni ( назад)
Nonsense. It's turtles, all the way down. :)

Автор Christian Burwell ( назад)

Автор General-Idea ( назад)
Would It be possible to possibly do a short video one of your channels regarding Maglev trains? I know the science behind them isn't particularly advanced, but finding a good quality video about them seems to be non-existent.
Keep up the great Videos on all the channels!

Автор Alexander Ehn ( назад)
Great that you did this version!

Автор Pope ( назад)
It literally depends on the toilet. I live in the northern hemisphere and I've had toilets that go either way.

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