Pump Cavitation: Prevention and Cause




One of the most common problems in pressure cleaners of every make is premature pump failure, most often caused by cavitation.


What is cavitation on a pressure washer system? Cavitation is the formation & accumulation of bubbles in the pumping chamber on your high pressure pump & when these bubbles are put under pressure they collapse or burst which can create tiny but violent implosions inside the water effecting the surrounding parts.


The 2 most common causes of cavitation happening in your pressure cleaner system are internal bypassing and sucking air.

Internal Bypassing


Cavitation through internal bypassing happens when your pressure washer is running & the discharge line (gun and lance) isn’t releasing water this causes the water to recirculate internally in the pump manifold, traveling through high and low pressure areas resulting in heat and high pressure, causing vaporised air bubbles or cavitation.

Sucking Air


Cavitation through sucking air can be caused by many things. Common culprits are the inlet fittings on your pressure cleaner not being tight enough, or not being sealed properly causing air to be sucked into the pump.  Un-maintained seals in your pump, bringing in water swishing it around & again causing air bubbles that can damaged internal components. While it only takes one, a combination of symptoms can cause cavitation.

Pressure Washer Pump Breakdown with Components Labelled



The immediately visible results can vary, such as decreased water flow, pressure dropping below the rated level, vibration in the line/gun as the small bubbles send their tiny explosions through the line, and cracking noises as when the bubbles implode.


While there are too many causes to give you an accurate picture here, some of the best ways you can prevent cavitation are regularly checking suction hoses, pump inlet fittings, checking & cleaning inlet filters, increasing hose and inlet fittings sizes, not leaving the machine running while no water is being discharged and regular maintenance on your pressure cleaner pump.



Preventing cavitation will significantly increase the life and efficiency of your pressure cleaner, catching the problem when it starts and preventing premature pump failure later. It also helps ensure that your pressure cleaner runs optimally and improves the effectiveness and speed of your cleaning. The easiest way of doing this is to conduct regular preventative maintenance on your pressure cleaner.


At the OEM Group we offer preventative maintenance agreements to prevent downtime and improve your productivity. If you are interested in preventative maintenance on your pressure cleaner or are looking for training in conducting regular maintenance yourself, you can call us on (08) 9270 0200 or email us at service@oemgroup.com.au.