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:

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 He also made still images of the earth from the top and the bottom.

Thanks to Vanessa for filming in Sydney:


There was a study performed at MIT years ago ( 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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Author That One Weirdo ( ago)
I would like to point out that, when a toilet flushes, it spews e-coli into the air. That is why I close the lid when done.

Author shimmer ( ago)
is this a re-upload??

Author Kevin Velez De Villa Mejia ( ago)
Noooooo!!!!! It's boring like this, it's alot alot alot more fun to get 2 phones or tablets and making it yourself lol 😂

Author De'Ja Nickle ( ago)
Thx for syncing videos

Author ssundee85 ( ago)
i live in huntsville al

Author Landon Lovette ( ago)
Glad they showed the clip from Long Way Down where they did it on either side of the equator

Author Yashas ( ago)
What if a hurricane moves from the southern hemisphere to the northern hemisphere?

Author Herbert Ramirez ( ago)

Author 1chumley1 ( ago)
I wanted to see a nut-filled turd in one of those toilets.

Author Cameron Sipka ( ago)
this is amazing <3

Author po k ( ago)
Only one pool in each hemisphere doesn't prove anything. Thought I was on science channel :p

Author Michael Covington ( ago)
Piss green from the sci show can suck it

Author MDFlight ( ago)
and they only needed to try this 10 times to get their desired outcome, pretty good tbh

Author Jacob chamberlain ( ago)
What about at the equator?

Author Ryu Vincent ( ago)
this video could probably be the most beautiful video on YouTube just because of how entertaining 2 guys try to explain simple science (rocket science being the not simple one)

Author Chinese Communist Party ( ago)
recycled footage much?

Author Joel Shore ( ago)
It's interesting to note that at the level of a tornado, which is considerably bigger than a bathtub but still pretty small on the scale of the Earth, about 95-98% are said to rotate cyclonically (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere), but there is that small fraction of anti-cyclonic tornadoes.

Author Bryce William ( ago)
I literally heard the explosion of a flat earthers brain.

Author Naranbaatar ( ago)
tell me about what will happen in the equator

Author jiří ledvinka ( ago)
What if huricane move from one hemisphere to another? Will it dissolve?

Author Lamanite Flarpleston ( ago)
It bothers me that they only conducted this test once. There is a 25% chance that the clockwise and counterclockwise rotations were completely by luck.

Edit: I just read the description and realized that they did multiple trials.
Ignore me.
I'm stupid

Author ArtStone ( ago)
Now hang a pendulum from the ceiling and put a circle of wooden pegs on the floor to knock over

Author Antoon Veeve ( ago)
Thank you two guys for doing this.. excellent - myth busted!

Author yuuge biggly ( ago)
i knew this years and years ago. just by thinking. i thought it was aways common knowledge that there are too many disturbances and eraddic forces/ turbulants in a toilet or sink to prove the corriolous effect

Author ChaosN ( ago)
Flat earthers be like...

Author Mathias Reschauer ( ago)
Have you heared about foucaults pendulum? it is tze complete same thing, just that its easier to measure it zhat way. I have seen one in the Deutsches Musdum in Munich. Fascinating.

Author Old Time Farm Boy ( ago)
Actually, water, hurricanes, tornadoes, etcetera, all turn in the same direction no matter what hemisphere they are in. It only appears different because of the perspective that humans see them in each hemisphere.

The proof can be found using the index finger of each hand. Let your left index finger represent the northern hemisphere, point it down and rotate it counter-clockwise. Let your right index finger represent the southern hemisphere, point it down and rotate it clockwise.

Now slowly, while maintaining its clockwise rotation, turn your right hand so that your index finger is pointing upwards towards the index finger on your left hand so that it assumes the perspective of someone in the southern hemisphere looking at the rotation. At that point you will clearly see that both index fingers are turning in the same direction.

Rotation of water, winds, hurricanes, and tornadoes are determined by the earth's rotation in both hemispheres. They only appear different because of human perspective.

Author Maj Mat ( ago)
You'll have to go to the north pole and try it,see if it just dumps the water "or some other liquid that won't freeze" without rotation .

Author Deilson Peres ( ago)
But Earth is flat :/

Author Johnny MashUp ( ago)
Veritasium are you interested in a collab?

Author Reyner Godoy ( ago)
thats obvious
that's just a point of reference
for example ( just an example i dont know what's the direction of the rotation )
if you go to the north pole you will see it *spinning left*
and if you got to the south pole you will see it *spinning right*

but if you go to the north pole again and somehow become able to see the south pole water, in your perspective it is *spinning left and not right*

Author Kearvin Brix Alano ( ago)
SO its true that the earth isnt flat??

Author valaram chaudhary ( ago)
this thing blown my mind

Author Faris Kazim ( ago)
Flat earthers just passed out

Author Michael Kamat ( ago)
Next time try to add the coloring before you unplug the pool

Author THATONEBACCA33 ( ago)
so this raises one question, what happens if you have a pool spilt through the equator 50/50 and drain it like that

Author Black Profile Picture ( ago)
proof flat-earthers are wrong

Author Dejan Kober ( ago)
Just for good measure I would repeat this experiment few more times.

Author Omare Abadi ( ago)
i love those videos <3!

Author pippaknuckle ( ago)
So right at the equator there is no swirl?
I remember being near the equator and thinking that sinks drained slower there.

Author sam hansen ( ago)
i dont understand why the water nearest eh ecuator has a larger velocity and momentum than the water nearest the poles....

can anyone explain it simply?

Author Ebony Maree ( ago)
Stargazing Live Australia really could have used you, Derek.

Author Lachlan Hillard ( ago)
1:50 I like how the American uses the metric system, yet the Australian uses the imperial system.

Author Rabik R ( ago)
But Derek, earth is flat, your theory is invalid!

Author Fender Ignacio ( ago)
Still cool after a year 😎

Author K 6 ( ago)
Science is real...

Author Jared D ( ago)
Then it stands to reason that along the equator there would be no preferential direction.

Author Ayyy Lmfao ( ago)
These two fucked after

Author Liam Strand ( ago)

Author Filip Wessman ( ago)
It is about size. The bigger the pool, the bigger the Corriolis effect. If the pool gets to slow, other factors like micro currents, friction, air draft, the shape of the container etc will determine the rotational direction.

Author Stephen Kramer ( ago)
What does it take to PROVE something that is extremely subtle and sensitive to the factors that affect it? hmmmmmmmmm... Or, instead, what does it take to make something happen that confirms your pre-existing belief (that you actually know nothing about) so you can be happy and gay and make money making other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) so they can be happy and gay and make other gay people happy and gay about their pre-existing beliefs (that they actually know nothing about) ...

Author 5Zaft Mohd ( ago)
so what happens at the equator? it just falls down then?

Author CHICKENFACE411 ( ago)
my toilet doesnt swirl it just drains and the water comes back out

Author Frank Harr ( ago)
That was pretty awesome.

Author Rajan Rangarajan ( ago)
Justin, derrick: why didn't you find some to do one more setup at equator at the exact same time?

Author BubbleGuy92 ( ago)
I didn't realise that this was both videos synchronised, so I clicked the link in the description to do it myself.

Author Lejon Van Rhee ( ago)
i love this vid

Author Hans-Joachim Bierwirth ( ago)
But: If you view a photograph showing a flock of flatearthers made through a filter polarized clockwise on the northern hemisphere through a filter polarized counterclockwise on the southern hemisphere the flatearthers are gone!

Author RoScFan ( ago)
so what happens if you put the kiddy pool right in the middle of the north or south pole? im not joking. This could be used to pinpoint the exact north/south pole to within a few hundreds of a milimeter. and it is something that should be done.

Author JmmiP 20 ( ago)
2:06 "anti-clockwise"

Author This guy ( ago)
It's not the same but if it's your only choice, it suffices.

Author raju pittu ( ago)
True scientists...

Author Ihab Karim ( ago)
can u help by telling if i rotates water in vertical clyinder ,,what would happend in high speed rpm

Author Sol RT ( ago)
So much water wasted 🤔👎

Author MorningCrafter ( ago)
You are wrong. The water still has a lot of momentum in it. Those tiny movements can snowball and create that whirl. You should have done more tests than one.

Author Unknown Entity ( ago)
Don't ask the question you dingus. Just say it does. I can't even be bothered to watch.

Author Spacemole ( ago)
I love how the American measured the pool in Meters and the Australian-Canadian measured it in Feet. Maybe the world is spinning backwards :D

but what if you drain it in the equator? will it drain sideways?

Author Logan Luther ( ago)
So we just need a really big toilet to see it...

Author Nathan Scott ( ago)
On the count of three everyone flush your toilet.....
1...... 2......

..3! Ahhh your not even at your toilet.

Author Proletário ( ago)
thats insane

Author Sgipon ( ago)
lmao! it's flat and unmovable. that's the truth

Author diGritz1 ( ago)
Clearly another attempt by NASA to hide the truth about poopy swirling vortexes of death. WAKE UP SHEEPLE!

Author upplsuckimcool16 ( ago)
if you try this exeriment precicely on the equator......... the water will explode.

Author upplsuckimcool16 ( ago)
This is what I've hear as well, however, I always just thoguht it had to do with which way the jets in the toilt bowl shoot out....

Author Marcus Ellis ( ago)
So what if half the pool is north of the equator and half is south of the equator?

Author Barti ( ago)
I enjoyed it back then...Enjoy it now...awesome.

Author Arnab Animesh Das ( ago)
Awesome speech sync. Gr8 vid as always.

Author QueenDaisy ( ago)
Two data points isn't really sufficient to prove anything; let's say that the direction of draining was completely random, there'd be a 50-50 chance one would conclude (from only two data points) that water always drains in the same direction no matter which hemisphere one is in, and a 50% chance one would get a false positive result that the direction does depend on the hemisphere one is in even if it doesn't.

Author BloodTar ( ago)
But I thought the earth was flat?

Author mc vid's ( ago)
In England our toilets don't spin the water

Author Ramazan Samat ( ago)
2 displays have better effect

Author Alain ( ago)
3:19 Coriolis effect

Author TheOriginalJoneser ( ago)
I have been subscribed to you BOTH of you, for Years, and this is one of the best collaborations of science on Youtube, EVER.

Author GG2K7AU05 ( ago)
Please also do a video about the weight difference at places like Finland (closer to pole) vs places like Brazil (at the equator).

Author Umberto Fournier ( ago)
so much science

Author MineGAGGER ( ago)
If this were totally random there would be a 25% chance that you would get this result so the experiment isn't really proof.

Author Master Of memez ( ago)
what about on the equator ( ͡o ͜ʖ ͡o)

Author Toveri Juri ( ago)
Never thought that a video about toilet water would be this interesting...

Author Alexander Provias ( ago)
*Question:* How big should an object be in order for us to see it if, theoretically, it's moving with the speed of light.

Author TheRadical Gamer ( ago)
What if you're ON the equator?

Author ironcityblue ( ago)

Author pyroguyman096 ( ago)
Can hurricanes cross the equator as they are forming and swirling, and if so, what happens? Does it disperse, like stirring a pot of water and then immediately switching directions, or would it maybe split off into two masses swirling opposite one another?

Author Pratik Patil ( ago)
+Veritasium Maybe you could do a video on the cooling of water in an earthen pot with infrared cameras and also a video on the wringing of the slip gauges ☺

Author Christopher Lusher ( ago)
For fun, sometimes I convince a person that only specialized helicopters can fly across the equator. First, talk about the Coriolis effect on draining water. Then say something like, "Due to the Coriolis force, the aircraft must be equipped to instantly reverse blade rotation to continue flying." haha, see if you can do this with a straight face!

Author givememore4free ( ago)
Thank God you did this video. It was really hard to sync the videos together.

Author dfjshjkd ( ago)

Author Mark Murphy ( ago)
what a bunch of crap

Author kejo miyake ( ago)
Unless you live over the Equator.

Author Thiago T ( ago)
and I'm here in Brazil, with my toilet flushing straight down like a river...

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