Check out this tank.

[wckdkl0wn]

This just doesn't seem possible. I read the site and under stand how it works but still.

http://www.cosmicbuddha.com/adam/archives/002230.html

 

[justintrask]

been posted here manyy times

 

[Juxtaroberto]

Hmmm... well if the top of the tank is sealed then the water can't come rushing out because for water to drain out air would have to move to the top of the tank, that's why they put the top of the feeder hole below the level of the feeder bowl. Does that make sense? Water comes out of the hole until it surpasses the top of the feeder hole, and since no more air gets in no more water comes out because the water would have to overcome the strength of the vacuum and water can't do that. That's why if you take a cup, dip it sideways in water so that it fills up, then point the mouth down and pull the cup up, the water doesn't rush out until the whole cup is out of the water.