Drains.
the water level would sink. Anything that sinks into the water would cause the water level to sink
water displacement
It goes down the toilet but if you go in the sink it goes down the drain.
You pray there is enough gravity to allow the water to drain
yes they can go in a sink of water and a bath tub but make sure that the drain is plugged just in case they lose a body part that it doesn't go down the drain
i think they go down the pipes and then it is sort of reused again by going through the water cleaning system
If the meaning behind your question is "does the water go clock-wise or counter clock-wise down a sink or toilet" then the answer is, it depends on the design of the sink or toilet, try this yourself, fill a sink up, pull the plug, when the water is going down (say clock-wise) swirl you finger in the water counter clock-wise and the water will go down that way, proving that it does not matter.
sink (to sink down), slide (to slide down)
A blocked pipe. The water can not go down the pipe, so it comes out in your sink.
Dive.
Because it is not like air where you can just breath and it goes down your throat.