Common mistakes to avoid when using a pressure washer

From using too much pressure to choosing the wrong nozzle, these are easy mistakes to make – whether you're just getting into pressure washing or you're a seasoned pro. 

Doing these things too often will not only give you poor cleaning results, but could also damage the surface you're cleaning. So read on for tips on how to make the most of your appliance.

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Avoid blasting water directly at the dirt

A pressure washer can make quick work of cleaning a grimy patio or soiled car, but using it in the wrong way can cause damage. 

Holding the nozzle too close and blasting water directly at the dirt will make the dirt fly everywhere if you're dealing with a particularly messy surface, and it can also erode the surface you're trying to clean. 

Blasting sand or mortar between paving slabs or paving sets can also allow in weeds once it's been removed.

Discover the best products to deal with weeds in paving and paths

What to do instead

• When cleaning a patio

Maintain an appropriate distance from the surface and adjust based on cleaning requirements. Fit the appropriate lance; most have a simple bayonet fitting. 

Work from one edge or corner of the patio, blasting the dirt away from you in a sweeping motion. If necessary, use the most powerful setting or the rotary lance to shift ground-in dirt and grime, but still keep some distance. Rinse off using a lower pressure.

• When washing a car

Use a variable jet-nozzle setting, which will make it much safer to clean different parts of the car without causing any damage. Adjust it to a spray of approximately 5-8cm wide. 

If you don't have a variable nozzle to adjust the power and width of the spray, stand at least a metre from the car. The distance will help to prevent any damage.

Need a new pressure washer? Head straight to our round-up of the best pressure washers

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Don't use the wrong nozzle or setting

When using a pressure washer, it's important to use the right setting and nozzle for the job you're tackling. Consider the material you're cleaning to choose the right one.

Opting for the wrong setting can result in damaging the surface. Whether you're cleaning your car, a wooden deck or paving, you'll want to adjust the pressure, select the appropriate nozzle and use the correct cleaning technique. 

Consider using an adjustable nozzle as it allows for more flexibility: you'll be to change the spray pattern without switching to a different nozzle.

What do do instead

• Wooden surfaces

Even if your timber and wooden surfaces are treated to protect against the elements and moisture, they'll still need regular cleaning. Some pressure washer manufacturers recommended a basic clean twice a year. A wooden deck should be cleaned at the start of the gardening season in spring, and again in autumn to prepare the surfaces for winter. 

Decks, patios, fences and sheds can be cleaned with a 25-degree or 40-degree nozzle for a wider spray pattern.

A pressure setting between 500 and 1,200 PSI is best for these types of surfaces. Use lower pressure for softer woods, such as cedar or pine. 

Keep the nozzle at least 60cm away from the surface and move in closer if needed. Make sure to spray along the grain of the wood.

• Concrete and brick

Use a 0-degree nozzle for tougher tasks such as cleaning particularly stubborn stains, or if you need to reach high spots. A 15-degree nozzle is recommended for general cleaning on concrete or brick.

The pressure setting will depend on the surface, but somewhere between 2,500 and 3,000 PSI is best. Exceeding this could cause damage, so always make sure you start with lower pressure and test a small area of the surface.

Use a consistent sweeping motion as you work, and be careful to avoid damaging surfaces such as softer bricks – particularly when working with a 0-degree nozzle. Some types of bricks can withstand water pressure up to 200 bar but others can break under high pressure. Take extra care if there are any loose bricks or other damage.

You can also clean surfaces such as the exterior of your house with a pressure washer, but don't clean a single spot for too long as the water pressure could remove paint or cause damage. Stable lime and cement-render facades can be cleaned with a fan-jet nozzle that helps to avoid damage.

• Cars 

Vehicles can be cleaned with a 40-degree nozzle or a specialised car-cleaning nozzle or attachment. If you're using a machine with a variable jet spray, adjust it to a spray of approximately 5-8cm wide. You want the spray to be strong enough to clean the car but not to damage the paintwork. Use nozzle attachments that allow you to change the direction of the spray.

You can use a water-pressure setting between 1,200 and 1,900 PSI. You'll need to use a slightly wider and less powerful setting for the windows, lights and other fragile areas.

Keep the nozzle at least 60cm away from the surfaces as you gently clean. Use a special car detergent that will help to break down the dirt. You can also use an attachable car brush to make the job quicker. 

Avoid using too much pressure

Using too much pressure can result in unwanted damage to the surface. It can strip away paint, gouge wood and even cause injury if you're not careful.

What to do instead 

Always start by testing a small area with low pressure and sufficient distance to see whether pressure washing will cause any damage.

If you're not sure what type of pressure is appropriate for the surface you're cleaning, you can always start with the lowest pressure and widest spray pattern and then adjust as necessary.

Always follow manufacturer instructions and avoid spraying electrical components.

You'll find all the information about the pressure washers we've tested in our pressure washer reviews

Don't forget to leave detergent to soak in

If you want the detergent to do its job efficiently, you need to allow it to sit and soak for long enough.

What do to instead

Typically, you should let it sit for around 5-10 minutes. This will allow the detergent to loosen and break down dirt without drying on the surface.

Always ensure you rinse thoroughly to prevent streaks or residue, and follow specific instructions provided with the detergent and pressure washer to achieve the best results. 

When cleaning a car, let the detergent work its magic for a few minutes, but again, don't let it dry or you'll be left with marks that will have to be buffed out later.

Don't use the wrong detergent

If you do, it will mean your clean will be less effective, but it can also damage the surface that's being cleaned or even the pressure washer.

What to do instead

Different surfaces require different cleaning agents, so only use detergents designed for the surface you're cleaning. Check the pressure washer's manual for any specific recommendations or restrictions.

It's also best to avoid mixing different detergents unless specified by the manufacturer.  

Always test a detergent on a small area first, and make sure you rise thoroughly after applying detergent.