KarcherK4 Power Control Car and Home

How we test surface cleaning ability

The overall cleaning performance takes into account both the best cleaning performance achieved by the main lance (or other accessory if it was better) and whether any damage was caused to the surface being cleaned. Generally we used the fan-jet nozzle for cleaning. The star ratings shown for cleaning each surface are purely based on how clean they were after the test. We found that when pressure washers were used according to the instructions, they did not cause any damage to the surfaces.

How we test ease of use

The overall ease of use takes into account how easy it is to use the presure washer in a number of different cleaning scenarios including assembling the pressure washer for the first time, and for using with the main lance and patio cleaner (if supplied). We also rate the ease of cleaning a car with the main lance or car brush (whichever is better) and how easy it is to manoeuvre and store the pressure washer.

How we test quietness

Quiteness is a subjective rating evaluated on how annoying and intrusive the noise that comes from the pressure washer is. It's measured in decibels 1m from the pressure washer motor and nozzle.

How we test water efficiency

This takes into account the water flow rate in l/h. You might want to avoid a one or two-star model if you are on a water meter and will use your washer for a long time.