Water swirls because it’s the course of ‘least action’ for the draining process. It creates a laminar and continuous volume exchange through a hole. Pipes are usually filled with air which has to be exchanged with water to drain. Physics just optimizes itself to be as efficent as possible with this. You can’t have a perfect draining surface so so currents in one direction will always be a little bit stronger that in the others. Gravity applies a constant acceleration, so this small difference in initial direction will be amplified over time creating a swirl.
In case of a toilet though, the water is already introduced in a swirl during flushing. So none of the above even matters.
Otherwise people on the equator, their toilet water wouldn’t spin at all? It would just go straight down, no spin.
Water swirls because it’s the course of ‘least action’ for the draining process. It creates a laminar and continuous volume exchange through a hole. Pipes are usually filled with air which has to be exchanged with water to drain. Physics just optimizes itself to be as efficent as possible with this. You can’t have a perfect draining surface so so currents in one direction will always be a little bit stronger that in the others. Gravity applies a constant acceleration, so this small difference in initial direction will be amplified over time creating a swirl.
In case of a toilet though, the water is already introduced in a swirl during flushing. So none of the above even matters.