PSI (Pounds per Square Inch) measures water pressure—essentially how hard the water hits the surface that is being cleaned.

will require more pressure than an electric model can provide. In addition to overall pressure, you should also check the “flow rate,” or the volume of the spray from your pressure washer.

But to err on the side of caution, a lower PSI model is more recommended. Besides performance, Ryobi's High Flow Automotive Pressure Washer comes with accessories different from the 1800 PSI and ...