Water dispenser plays important role in restaurants, hotels, offices, etc. And it is the perfect example to demonstrate Air Pressure. Water dispenser is useful to supply normal to moderate to hot water whenever we press button. Water dispenser is a set-up of upside down 4-5 gallon water bottle at the top of the machine. Mostly, water dispensers work by pressing button, through which you are increasing the pressure inside by allowing the air inside the bottle. And that’s the way, you can dispense water from the machine when air allowed inside the bottle.