Here’s how the water flows through a high pressure cleaner.
The water supply from a holding tank, or directly from a tap, feeds the triplex pump. This must be clean water, so there is a filter before the pump inlet.
When the pump is running water is by-passed until the gun trigger is activated.
A low water control may be fitted in the supply tank. This will cut the engine or motor to prevent accidental dry running of the pump.
The pressure is generated by the compression of the water as it leaves the end of the gun lance through a nozzle.