The Truth About Toilet Swirl - Southern Hemisphere

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Some notes:
We each repeated the experiment 3 times, and got the same results every time. For those of you who might be skeptical, great! A right circular prismatic kiddie pool is only $10 and you can do the experiment for yourself at your latitude. There's really no reason you shouldn't do it for yourself.

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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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Runtime: 8:3
Comments: 5869

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Author Chad Kennow ( ago)
This was awesome Derek! :) Keep up the great work! :)

Author Rodrigo Velásquez ( ago)
You guys should both travel to Ecuador and set two pools , one just north of the equator and the other just south, and make the same experiment. And you could add a third pool, in the very equator. And see what happens too. It should be awesome to see them at the same time spinning in diferente directions. Regards....

Author Rodrigo Velásquez ( ago)
Simplemente espectacular... que ingeniosa idea la de los 2 videos, felicitaciones

Author Christopher Smallwood ( ago)
you have my subscription. awesome videos you did with Destin. well done.

Author tinkmarshino ( ago)
you guys are crazy fun!

Author Melvin Duckenfield ( ago)
At 4:08 he states, "So really you're not gonna see it in a bathtub and you're not gonna see it in a sink or in a toilet because there are other sources of angular momentum that totally wash out this effect." What are those sources? It appears to me that there are multiple variables to be considered before one can definitively "prove" the desired conclusion. Additionally, only one experiment was done. Can we draw a definitive conclusion based on one experiment? Could the direction of the air current above the pool, since it was outside, have affected the direction in which the water drained? Were both platforms identical and completely level? I would be more inclined to consider his conclusions if he and his partner had repeated their experiments multiple times under various conditions and in various locations in the respective hemispheres to prove their hypotheses. Isn't that what the scientific method is all about?

Author Cody Deforest ( ago)
That was cool guys

Author Zephree Zen Gold ( ago)
great team work see my comment on smarter everyday

Author mike nguyen ( ago)
the screen warp was pretty sick

Author DMatthewHenry ( ago)
This was really freaking cool.

Author ShadyNinjaGaming ( ago)
Brilliantly made
(other vid) - every day

Author jakub Kraus ( ago)
Too bad the Earth is obviously flat...


Author Koenshakuable ( ago)
that was... (on the other channel)

Author HOPEFOR TRUTH ( ago)
what a load of nonsense

Author Z_E_D ( ago)
Awsome Double video experience! The timing can't have been easy! =)
Great job! and fun to learn

Author Xero ( ago)
cringy end

Author daniel hoad ( ago)
this is to much effort to know which way a toilet flushes

Author Robert crowdiver Burns ( ago)
horseshit,, it does the same up north !

Author Ananthan S Menon ( ago)
this comment is here.
find it

Author Ryo Ryo ( ago)
this video is creative...

Author Sam Peterson ( ago)
I love what you guy's did with this video!!!! So smart and awesome! I've been subscribed to both of your channels for some time now... glad to see two of my most entertaining choices working together.😁 thanks guys!

Author lol 231 ( ago)
awesome video

Author Ya Mi ( ago)

Author Sean Freeman ( ago)
that was dope af

Author Mahbub clickin' ( ago)
i watched both videos chronologically on a single screen, one video after the other, so the real drain happens on my brain.

Author Benjamin Hershey ( ago)
Protip: put Destin on the left and Derek on the right for proper orientation.

Author Connieisland0 ( ago)
This is video is so misleading and untrue. It throws the scientific method out the window.
Water spins according to the shape of the drain, its immediate surrounding. Sadly the masses will be believe a video like this more than making the experiment themselves.
If people think that earth rotation is detectable by no other instruments but a simple water flow going down a drain, then they should really do a check up with the reality around them.
There are no instruments that ever detected the rotation of the earth, however you're telling us that water going in a drain gets affected by this so called rotation??

Author Сергей ( ago)
In my bath it always swirls in one direction. Even if i try to change the swirling direction with a stick or smth like that, water changes the direction again to the initial one after a minute or so.

Author ToastyRoland ( ago)
Sync these videos up.. it is extremely worth it. Cheers.

Author Cthulu Muramasa ( ago)
Just learned this in science

Author Cthulu Muramasa ( ago)

Author Cthulu Muramasa ( ago)
It's the Coriolanus effect

Author bleuthoot ( ago)
This is the ultimate way to collaborate

Author Everybody90 ( ago)
hello from

Author Sirake Wizen ( ago)
Damn, I'm already subscribed to both :(

Author D-Schloss the boss H-town rowlin hard ( ago)
how did you know i put you on the right

Author RegularBrady ( ago)
Loved the syncing of the videos, super fun!!!

Author Rrroonald Weasly ( ago)
Perfect sync, first try. MVP.

Author Antony Theriault ( ago)
Really cool videos guys, but geez do you not realize how hard it can be to sync two videos on the same computer?

Author koplerio ( ago)
time same the go both make to able not I'm If Sucks. (northern Hemisphere)

Author CRaSHeCLiPs ( ago)

Author Mate Rodić ( ago)
soo cool

Author Dartnix ( ago)
One of the best ideas I've seen on youtube and very well put together!

Author Screaming Match ( ago)
Ya'll did great!

Author Dj2xP ( ago)
Hahaha, I have a dual screen setup so synching these was not hard, but I chose to put Veritasium's video on my left screen, which broke the immersion at the end :D

Author Ali Tahrei Sh. ( ago)
What about equator?

Author qwchrbichn ( ago)
The truth about toilet swirl is that toilets force the water in one direction or another. The side-by-side sink comparison is hardly surprising. A better side-by-side comparison would be ones with drains in the center of each compartment.

Author Barnaby Jones ( ago)
This is one of the best uses I have ever had for my second monitor :)

Author Liza Marie Rios ( ago)
omg you guys are awesome.

Author Bron Cinzah ( ago)
're amazing ...if you follow this you're Genius...

Author FuckYouGooglePlus ( ago)
This is jus silly. A 12 foot pool is NOT showing off the Coriolis effect. The effect on something that small would be way more than canceled out by imperfections in the pool itself. Like not being level, or any deviations from roundness, etc. Even imperceptible wind.

Author silikonmanufaktur ( ago)
Wow, didn't think it would really work ! Amazing. Did you try several times to make sure it wasn't just a lucky coincidence ? Best way to do it would be using several pools at the same time, to make sure no tiny asymmetry in the outlet, the valve, the plug etc determines the direction of the rotation. Because that might easily be the case, considering the incredible tiny difference in angular momentum we are talking about. And air has a lot less friction compared to water, while the distances covered by those storms are hundreds of miles ! I must confess i would have bet money on you guys failing to show the coriolis effect in a kiddie pool ! Congrats and well done ! :-)

Author Tej Pal Singh ( ago)
all my favourite people in one video.

Author jon pounders ( ago)
why didn't you guys do the same test in the northern hemisphere to make this study complete?

Author Seán Mercier ( ago)
Hey guys, wanted to say I've been watching both of your channels for a while now and just stumbled across this. Being from a Video making background, I found this synchronised fusion really exciting on top of your usual high quality content. Thanks for doing what you do!

Author DR. NEO ( ago)
the sync was amazing

Author Vincent Paul ( ago)
I synchronized the video and it was very interesting.

Author Brian Killough ( ago)
could we place something low that would hardly if not at all be affected by wind to flow to a specific spot in the ocean? Is the pool and the hole in perfect symmetry and perfectly level?

Author Death_Kenny ( ago)
Got it timed perfectly first try... Really amazing Idea of you both! Loved it!

Author Maven Sony ( ago)
Now do this experiment in exactly midpoint of equator .Lets see what happens..

Author znatim ( ago)
You could mention Foucault experiment

Author sharan kaur ( ago)
Happiness when u r subscriber of both channels 😆

Author kuonirat ( ago)
Now I can impress my female colleague, who claimed otherwise.

Author Southern Hemisphere ( ago)
Name stealer :(

Author Strike Eagle ( ago)
Im subbed to him but i still dont know what i am doing with my life

Author Strike Eagle ( ago)
That... Was... AWSOME! The 2 vid idea was crazy cool!

Author MrG ( ago)
what a great idea! You both are awsome guys. I allways said the internet is a huge dunghill where here and there thrives a flower. You are these flowers I was seeking. Stay smart and above all, stay curious.

Author zazke girotron ( ago)
hey this is cheating: 2 views at the same time per person... well played

Author oceanceaser ( ago)

Author Dean Stewart ( ago)
Champion effort guys

Author mrcleanisin ( ago)
I haven't read all the comments, but surely someone asked them why they didn't repeat the expirments more than one time?

Author Roan Wilkins ( ago)

Author Mohamad Zaid ( ago)
nice..i did sync both video with two monitor. haha burnn

Author ANDROID GAMING ( ago)

Author Al-mujahedeen Salahadeen ( ago)
SmarterEveryDay brought me here!

Author MWB Gaming ( ago)
1:32 you are not here in AU
our power outlets look like an arrow not like the face of someone getting probed

Author dan hewitt ( ago)
Who else subbed from smarter every day? Great channel btw? I like ur vids alot. 😊 peace from the UK

Author farooq shaik ( ago)
Open Two tabs and cascade

Author Abodimax Alrashdi ( ago)
what will hAppen if you. we're on the. equator

Author Gabri Janse van Rensburg ( ago)
This was so cool. I got it to sync up exactly on my first try. You guys are awesome.

Author Dj Otsirave ( ago)

Author Agusta Motor ( ago)
That is also the reason why australians drive clockwise on roundabout, and Americans drive anti clockwise

Author EmeraldGaming ( ago)
Too bad this doesn't work on mobile

Author gmeast ( ago)
yeah ... I figured this out on my own in my 1965 high school physics class. What's the big deal?

Author MinerQuick ( ago)
Wow that was Impressive 2 vid in 1

Author Michael Scofield ( ago)
Awesome project guys, loved the synced videos

Author Abishai Singh ( ago)
Really creative way of collaborating and I was fun watching both the videos simultaneously in 2 different tabs. Hope to see more vidoes....

Author pietersrv ( ago)
So there IS an effect!

Author Sasami R Conway ( ago)
so cool

Author Kristjan Niiberg ( ago)
awesome guys!!!

Author ThePiGuy24 Gaming ( ago)
This is an awesome half video.

Author Coffee King GT ( ago)
read my comment on the other vid

Author Enchanter 101 ( ago)
i sync it

Author Derrick Wesonga ( ago)
I had it perfectly synced then about 4 minuites YOUTUBE had to show me an AD on one video :(

Author Leonardo Nerio Benavides ( ago)
What if you plug it straight in the middle of north or South Pole, does it go out without spinning?

Author TheFalconLord ( ago)
I like how these two awesome channels are trying to help each other get views XD

Author A Duck ( ago)
ʕoɘbiv ɿɘʜɈo ɘʜɈ no ʞool lliw Ɉnɘmmoɔ ƨiʜɈ woʜ ɿɘbnoW

Author Devilmonkey ( ago)
strange how Veritasium used the term 5' foot wide (in a metric country) and Smarter every day used 1.5 meter (in an imperial system country) as their units of measurement.
This is why we crash space probes people!
Just thought it was odd.

Author Seanisawesome000 ( ago)
Brendon wish me luck!
Other video: good luck derek!

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