There are many different types of water pump, however the most common are positive displacement varieties, such as the manually operated piston pumps which are often found in parks, as well as developing countries.
Positive displacement pumps work by trapping water from a central reservoir and then forcing its volume upwards into a discharge pipe. This is achieved most commonly through the use of a valved piston and cylinder, which when combined, draw water via suction up into a cylinder, before redistributing it through a descending valved piston head into an expanding higher chamber.
When the piston begins to rise, its own valve is forced shut by increased pressure within the higher cylinder chamber, while the cylinder’s reservoir valve is pulled open by a release of pressure in the lower chamber.
This allows pockets of water to be continuously drawn up from an underground source to an outlet on the surface.
Historically, water pumps were invented to optimize the retrieval of water from town wells, which previously had employed simple but labour-intensive bucket-on-rope methods.
Water pump parts
Check valves – The check valves are one-way, non-return valves, and allow water to pass through first from the reservoir and second through the piston head on its journey to the surface.
Cylinder – The vertical body of the pump, the cylinder provides an enclosed compartment for the pump’s piston to move through.
Piston – The piston descends and ascends through the cylinder, with water from the lower chamber forced through its head valve via an increase in pressure.
Reservoir – A mediating tank or chamber where the pump’s water is stored ready for extraction.