text: a water dispenser for pets has an inverted plastic bottle.? when a certain amount of water is drunk from the bowl, more water flows automatically from the bottle into the bowl. the bowl never overflows. explain the operation of the dispenser. does the height of the water in the bottle depend on the surface area of the water in the bowl? in a vacuum (assuming the water didn't boil) the water level of the bowl and the bottle would be equal. however, the air pressure on the water in the bowl pushes the water up and back into the bottle. it's a constant battle between gravity and air pressure, which is determined by the surface area of the water in the bowl.