How much water does a pressure washer use?

Are you considering buying a pressure washer and are concerned about water usage, do you think that you might use a great deal more than a few buckets full for the weekly car wash?

Maybe you are concerned for the environment, or you might have a water meter fitted and want the best way to get a high quality clean without watching the pennies clocking up at an alarming rate?

I’ve put together a few facts and figures to hopefully help your decision making.

Obviously, the amount of water used depends on variants; how big is the cleaning area, how many layers of dirt and grime need to be washed off and how long will you be using your pressure washer for?

The method used to measure water flow from appliances is:

Bosch AQT 33-11 High Pressure Washer


Using this method, a standard electrical pressure washer, the type regularly bought for use around our homes and gardens, uses 1.6 GPM, which is remarkably less than the 5-10 GPM a standard garden hose uses. Using a spray attachment on your hosepipe brings the usage to the lower end of the scale.

A medium duty pressure washer will usually use between 2.3 and 2.5 GPM and a professional, heavy-duty piece of kit can use anywhere between 2 and 4 GPM.

The average shower uses around 2.5 – 3 GPM, so what’s the difference between a shower head and the nozzle of your pressure washer……..? Pressure!

Pressure is measured by weight


Creating intense pressure makes the water form a stronger stream.

The jet can be so powerful that it completes the job in a fraction of the time. Therefore using less water.

Purchasing a pressure washer with a higher pressure rating doesn’t always guarantee a more powerful wash or a reduction in the amount of water used, let me explain.

Electric compact model                 –   3.5 GPM     2000 PSI   = 7000 CU

Multiplying these figures together gives you the CU, Cleaning Units

Professional heavy duty model    –    2.3 GPM      2600 PSI    = 5980 CU

A combination of both of the figures gives you the sum of the machine’s capability.  Despite the electric one having less power, it would have got the job done faster.

(Check out our article comparing the best pressure washers)

The higher the CU figure establishes the more water efficient, better quality and faster your cleaning should be.

In the garden

If you currently use a standard garden hose to wash your car or windows, you will be using between 5 and 10 gallons of water per minute with a pressure rating of 30 – 50 pounds per square inch. Compare this to using a compact standard electric pressure washer with a PSI of 1750 and 1.6 GPM, you will have between 5 and 18% more cleaning power and be using 68% less water!

If all the figures and abbreviations are making your head spin, it means that yes, you will use a lot of water, but as the pressure is so strong, even the most stubborn stains will clean away in a much shorter time than just using a hosepipe!

How to maximise water efficiency

There are always ways that you can save more water when using your pressure washer, for instance, getting the job prepared beforehand.

As spring rolls around I find myself gazing out at my patio, during the summer is clean and inviting, but after winter has taken its toll, the slabs are filthy, mud strewn and moss from the guttering is nestled in every crack.

It’s time to put my wellies on!

Before I even attempt to begin pressure washing, I sweep everything off and pour detergent over the patio, then using my hard yard brush I give it a good scrub.

This makes for a layer or two less for the pressure washer to have to tackle, and also, by loosening all of the grime, makes it an even quicker job, therefore less water is consumed.

Using the correct nozzle attachment makes for a more efficient job , using a nozzle with a wide angle is ideal for light cleaning, the car and windows etc.

Using a narrow angled nozzle will make the stream of water stronger, enabling you to do the real grotty jobs, pavements, brickwork and even my grubby patio!

No tap? No worries!

Did you know that no outside tap, or even no tap at all within a close distance, doesn’t render your pressure washer ‘out of action’.

If your machine is a model that is compatible with a Suction Hose Filter Kit, then you’re in luck. The hose is fitted with a non-return valve and is attachable to your water butt to use the harvested rainwater.

The filter means you can drop the pipe into any reclaimed water, a stream if you’re desperate, or even a plastic drum that was filled at an earlier date.

Water, water everywhere..

For those of us who take a bath every day, that’s a whopping 36 gallons of water on average that we’re using. Each!

 An old shower uses 5GPM, that’s 25 gallons for 5 minutes, though modern showers are designed to be water saving and use only 2 GPM. That’s still 10 gallons for a ‘quick’ shower.

How new your washing machine is decides how much water it uses, anywhere between 25 and a whopping 40 gallons per load!

So if we’re trying to be conscious and efficient, it would seem investing in a pressure washer from a reputable brand, used in the correct way, can be a very effective way to reduce how much water we are using.

Saving water!

Consider this, using your garden hosepipe for 20 minutes to wash the car and the windows at an average usage of 8 GPM could use a huge 160 gallons of water!

Using your pressure washer for the identical jobs could not only take half of the time, it might also take half of the elbow grease!

If it’s a standard 2 GPM model, 20 minutes use equates to 40 gallons of water.

That is a huge 75% difference!

You could always use the left over time to clean your partner’s car and earn some brownie points!