The maximum height of a siphon is when the weight of the column of liquid to the intermediate high point is equal to the atmospheric pressure. A siphon is a tube that allows liquid to drain from a reservoir through an intermediate point that is higher than the reservoir.
Siphons may be used to drain water after floods. Other practical applications are found in the municipal water industry. Scientists have compared several mechanisms in living organisms to siphons, such as blood circulation in giraffes and snakes. In these animals, blood that flows down the veins is thought to siphon blood up to the arteries.