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How we test pressure washers

By Victoria Pearson

Find out how Which? tests pressure washers to reveal which ones clean brilliantly, have useful accessories and are easy to use.

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In this video you'll 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 washers take the risk out of choosing a new pressure washer. 

Our reviews answer the most crucial questions about pressure washers:

  • How well does the pressure washer clean?
  • How easy is the pressure washer to use?
  • Which version should I choose?
  • How easy is the pressure washer to move and store?
  • Should I buy it?

Find out which machines give top class results in our pressure washer reviews

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, and softwood decking. 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.

We also assess how well the pressure washer cleans the bodywork, windows and wheels of a heavily soiled car.

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.
30The number of aspects we rate to decide how easy it is to use each pressure washer, from attaching the lance to winding the hose up to put it away.

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).

You can find out more about these features by reading our guide to pressure washer features explained.

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.

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.

Visit our Karcher pressure washer reviews or Vax pressure washer reviews to see this in action.

We determine whether 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.

Patio cleanersOften make cleaning quicker but less thorough than the main lance.

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?

75%The score a pressure washer needs to earn to be considered as a Which? Best Buy.

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 washer needs to score at least 75% to be considered a 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. 

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