Cavitation
Cavitation is the formation and violent collapse of vapor bubbles inside a pressure washer's pump when the water supply is insufficient, the inlet is restricted, or the water temperature is too high. When the pump pulls harder than the water supply can feed it, low-pressure zones inside the pump drop below water's vapor pressure, bubbles form, and then implode as they hit the high-pressure side — each implosion a tiny hammer striking the pump's internals. Sustained cavitation destroys pump seals, valves, and the manifold itself in hours.
In depth
Cavitation is the #1 cause of catastrophic pump failure in the field. Symptoms include a rattling or pulsing pump, erratic pressure at the nozzle, and visible shaking of the pump head. The fix is almost always upstream: a larger garden hose, a pressure-boosted buffer tank, a cooler water source, or a cleaner inlet filter. A professional knows to listen for early cavitation and shut down immediately — a single hour of sustained cavitation can destroy a $1,200 pump.
How this shows up on our jobs
We run pressurized buffer tanks on all of our trucks specifically to prevent cavitation. A bad municipal hose bib on an old Madison home can starve a professional pump in minutes.
Services where this matters
Related terms
GPM (Gallons per Minute)
GPM stands for Gallons Per Minute — the volume of water a pressure washer delivers per minute of operation. While PSI gets the headlines, GPM is what actually does the cleaning. Think of it this way: PSI is the hammer's strength; GPM is how many hammers you're swinging. Higher GPM means more water flowing across the surface, which means faster dirt removal, better rinsing of detergents, and shorter job times.
PSI (Pounds per Square Inch)
PSI is the unit of pressure used to rate pressure washers, measuring the force of water exiting the pump per square inch of surface area. Consumer pressure washers run 1,500-2,500 PSI; professional rigs typically produce 3,500-5,000 PSI; and specialty surface cleaners can spike above 8,000 PSI. Higher PSI is not always better — in fact, for most home exterior surfaces, high PSI is destructive. Vinyl siding, wood shingles, soft mortar, roof granules, and painted surfaces all fail under excessive pressure.
Hot Water Pressure Washing
Hot water pressure washing uses a diesel-fired burner to heat the pressure washer's output to 180-200°F before it hits the surface. The physics is simple: hot water dissolves grease and oil, accelerates chemical reactions, lowers the dwell time needed for detergent to work, and kills biological growth on contact. Cold-water pressure washing relies on mechanical force and chemistry alone, which means longer jobs and lower performance on greasy substrates.