A small question for you down-under folks

[TarnishedPenny]

A trivial question, but one for which my Google-fu has provided conflicting answers and I’m still curious. When water goes down the drain in your sink, which way does it spin - clockwise or counterclockwise? Thanks.

 

[CalebZhass]

A trivial question, but one for which my Google-fu has provided conflicting answers and I’m still curious. When water goes down the drain in your sink, which way does it spin - clockwise or counterclockwise? Thanks.

I asked Dr. ChatGPT for you. You're welcome:

The rotation of water in a sink, often observed when the water is draining, is commonly referred to as a vortex. The direction and pattern of this rotation can be influenced by several factors:

1. Coriolis Effect: On a large scale, like in weather systems or ocean currents, the Coriolis effect (due to the Earth's rotation) can influence the direction of rotation—cyclones spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. However, in small systems like a sink or toilet, the Coriolis effect is generally too weak to influence the water's rotation.
2. Shape and Angle of the Basin: The shape of the sink or basin and the angle at which the water is introduced can influence the direction of the vortex. If the basin has any asymmetry or if the water flows into it at an angle, this can set a preferential direction for the rotation.
3. Initial Motion of Water: The way water was initially moved or stirred can set the direction of the vortex. For instance, if water in a sink is given a slight push in a particular direction, it tends to continue spinning in that direction as it drains.
4. Local Conditions: Other local conditions, such as the design of the drain, obstructions in the water, or even slight vibrations or drafts in the room, can influence the direction of the water's rotation.

In practice, for sinks and bathtubs, the direction of water rotation is more likely to be determined by local conditions rather than any large-scale physical forces. As a result, the water can rotate in either direction, and there is no universal pattern for the rotation of water in a sink.

 

[jaF0]

I asked Dr. ChatGPT for you. You're welcome:

So, you yourself, do not have first hand knowledge, correct?

 

[AwkwardlySet]

The Coriolis effect has only a minor influence on the direction the water takes when draining. The shape of the drain is significantly more important, so it is generally considered a misconception that water drains differently if on a different hemisphere.

 

[CalebZhass]

So, you yourself, do not have first hand knowledge, correct?

No, I wasn't south of the equator yet. However I have first hand knowledge from north of the equator and I know some physics, plus I am friends with ChatGPT. I find that combo to be enough usually.
If you are more interested in testimonials, then disregard my answer.
I figured you just wanted to clear up some confusion after googling.

 

[alohadave]

The shape of the drain is significantly more important, so it is generally considered a misconception that water drains differently if on a different hemisphere.

Water flow has an impact as well. I've changed the direction of water draining in my tub simply by swirling my finger in the opposite direction.

 

[MyBareTorso]

I just did it...anti-clockwise...but I have a hangover, and it's a really small sink, so I could be mistaken...

 

[ElectricBlue]

The Coriolis effect has only a minor influence on the direction the water takes when draining. The shape of the drain is significantly more important, so it is generally considered a misconception that water drains differently if on a different hemisphere.

Not strictly true. Water goes down the gurgler the opposite way to the Northern hemisphere - with the caveat that it has a visible swirl - which, as you say, might depend on the plug hole. Same with cyclones - they spin clockwise, south of the equator.

 

[AwkwardlySet]

Water flow has an impact as well. I've changed the direction of water draining in my tub simply by swirling my finger in the opposite direction.

Of course. The forces influencing the direction of the flow aren't very strong so the direction can change easily. The initial momentum of the water, the shape of the drain, the roughness of the surface... it all matters. Only if all of these things are at or near zero does the Coriolis effect come into play.

 

[AwkwardlySet]

Not strictly true. Water goes down the gurgler the opposite way to the Northern hemisphere - with the caveat that it has a visible swirl - which, as you say, might depend on the plug hole. Same with cyclones - they spin clockwise, south of the equator.

The Coriolis effect has much more influence on the fluids that move in large diameters. It has an influence on the direction the river flow takes as well, although once again, the shape of the terrain and its composition play a larger role.

 

[ElectricBlue]

The Coriolis effect has much more influence on the fluids that move in large diameters. It has an influence on the direction the river flow takes as well, although once again, the shape of the terrain and its composition play a larger role.

I eye-balled it in my kitchen sink, and saw the rotation quite clearly. So even with only two litres of water going down a two inch plug hole, physics works. Funny thing, laws of physics .

 

[jaF0]

^^^ What? No need for some silly chat thing-a-ma-doey? Actual, real time, first person eye-balling?

 

[SimonDoom]

Northern hemisphere here. I just flushed my toilet and it drained clockwise. That's a good enough sample size for me.

 

[ShelbyDawn57]

Northern hemisphere here. I just flushed my toilet and it drained clockwise. That's a good enough sample size for me.

Northern hemisphere here as well. i just flushed mine and it emptied. I'm good with that. The rest is irrelevant.

 

[TarnishedPenny]

Thanks, all.

 

[Rustyoznail]

Just read this while sitting on the loo. After flushing, too much turbulence from the incoming water to tell. Sink after washing hands - drains too slow to tell.

 

[Bramblethorn]

Under highly controlled conditions, there's a consistent Northern Hemisphere anticlockwise/Southern Hemisphere clockwise effect: https://www.australiangeographic.co...2016/06/which-way-does-water-go-down-a-drain/

But outside the kinds of conditions described in that article, the Coriolis effect at the scale of a household sink is so weak that the results will depend mostly on the shape of the individual sink, any movement in the water before it's drained, and just how the plug is pulled.

The "toilet flush" version is a red herring. The typical Australian toilet is designed differently to what Americans are used to and they flush differently; you wouldn't normally see any kind of spiral here.

Edit: I just tested it out in my bathroom sink, since I had some cleaning to do anyway. Can confirm that my sink goes both ways. Filled it, dunked a washer in it to wet it, pulled the plug, observed anticlockwise spiral; then repeated, this time moving the washer in the opposite direction, and observed clockwise spiral.

 

[jaF0]

Do it with a sink full of still, undisturbed water. At least a couple of gallons; enough to get some motion in the flowin'. Fill the sink. Let it set 10 minutes or more. Uncork. Let the water decide.

 

[lanceGibs]

A trivial question, but one for which my Google-fu has provided conflicting answers and I’m still curious. When water goes down the drain in your sink, which way does it spin - clockwise or counterclockwise? Thanks.

Try reading this


https://oceanservice.noaa.gov/educa...e Earth rotates,is called the Coriolis effect.

 

[Britva415]

I can't wait to see the consequences of this particular Chekov's Gun going off in the story.

 

[Duleigh]

I can't wait to see the consequences of this particular Chekov's Gun going off in the story.

I'm not sure about Mr. Chekov, but I KNOW that Han shot first.

 

[BobbyBrandt]

Wasn't the Darling Harbour Woodward water feature designed to reflect this very phenomenon?

 

[jehoram]

A trivial question, but one for which my Google-fu has provided conflicting answers and I’m still curious. When water goes down the drain in your sink, which way does it spin - clockwise or counterclockwise? Thanks.

The definitive answer to this question (at least for me) is this column written back in the 1980s by Cecil Adams for The Straight Dope:
https://www.straightdope.com/21341330/do-bathtubs-drain-counterclockwise-in-the-northern-hemisphere

 

[ElectricBlue]

Wasn't the Darling Harbour Woodward water feature designed to reflect this very phenomenon?

It certainly goes clockwise. It's great to see the kids running through it on a hot day. Although I don't know what it's like these days, not having been to Sydney for years.

 

[alohadave]

The "toilet flush" version is a red herring. The typical Australian toilet is designed differently to what Americans are used to and they flush differently; you wouldn't normally see any kind of spiral here.

Most American toilets operate on a water jet that siphons the water out really fast, the water doesn't swirl down at all.