Siphons can be used to move water with help from differences in levels, water pressure and the earth’s pull. If you gently shake the container to one side, there will be different levels in the containers. These different levels mean that the water in the top container is forced down into the lower container with help from the earth’s pull. The water will continue to flow until the water level is equal. If the tube is filled with water first, it is easier to start the siphon.
Where can you see this in everyday life?
Breweries use the siphon principle or hydrostatic pressure and the siphon phenomenon to move liquids between different containers.
Molluscs have a siphon that uses this principle. Water flows through the siphons in molluscs that live in water (such as gastropods and cephalopods), and air for molluscs that live on land (such as slugs and snails). The siphon is used to eat, breathe and reproduce, as well as to move.
If you empty an aquarium, it is easier if you use the siphon principle.