How we test pressure washers

Watch our video below to find out what it takes for a pressure washer to earn our coveted Which? Best Buy recommendation, and how a Best Buy could make a real difference to the cleanliness of your car or patio.

Some pressure washers come with a wide range of accessories that make them look like excellent value, but they do a poor job of cleaning surfaces and cars. Others look basic, but blast dirt from your garden pathways like a dream. 

The only way to tell if a pressure washer is any good is to clean a range of different surfaces with it, which is why Which? does exactly that in our independent lab tests. Our recommended Best Buy pressure washer take the risk out of choosing a new pressure washer. 

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Video: how we test pressure washers

How well does the pressure washer clean?

To find out how well each pressure washer cleans we wash a one-metre square patch of several different types of surface including concrete, block paving, paving slabs, softwood decking and even a car. The surfaces are consistently and heavily soiled to provide a fair comparison between models, and we use the main lance and fan nozzle to clean them.

We measure how long it takes and rate how clean the surfaces are. We also look for any signs that the pressure washer has damaged the surface, or material between slabs and paving blocks during cleaning. 

We're looking for surfaces that are completely clean, with no traces of dirt, stains, algae or lichen left behind. Washers are rated lower if they leave traces of moss or weeds between slabs, or dirt in the grooves of decking.

In addition we test what surface area of concrete can be cleaned in one minute. This allows us to assess the speed of the pressure washer which is especially important for anyone who wants to clean a large area quickly and isn't looking for a perfect clean.

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How easy is the pressure washer to use?

We assemble each pressure washer, rating how easy it is to put together the first time you use it, and also to assemble and dismantle it for normal use.

We rate how easy it is to set up and use the pressure washer to clean surfaces and a car with the main lance, and also using the patio cleaner (if provided).

Two further aspects of convenience that we consider are:

• Noise - we evaluate how irritating the noise level is while cleaning.
• Water economy - based on how much water the pressure washer actually uses while cleaning.

You can find out more about additional accessories in our guide on the best pressure washers.

Which version should I choose?

Pressure washers are often sold as different versions, with the same basic motor unit paired with a selection of accessories more suitable for home or car cleaning.

We determine whether the accessories, such as a patio cleaner or car brush, clean as quickly or well as the main lance to help you decide whether they're worth paying more for.

See full information of what version includes what in our individual pressure washer reviews.

How easy is the pressure washer to move and store?

We assess how easy it is to move the pressure washer, taking into account its size, weight and how well the wheels or handles work. 

Finally, we rate how easy it is to store, paying particular attention to whether the hooks or reels for the cable and hose keep them tidy.

Should I buy it?

Each of the assessments described above goes part way to making up a total test score, which is the percentage figure we award each pressure washer.

But certain assessments are more important than others and so carry different weights:

• 50% cleaning ability on surfaces and cars
• 30% ease of use
• 15% noise
• 5% water usage

A pressure washing needs to earn a score of 75% and above to be considered as a Which? Best Buy. Those scoring below 45% are highlighted as Don't Buy models and are so bad that we think you should avoid them altogether. 

Ready to pick your new pressure washer? Jump straight to our best pressure washers guide.