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How to use a pressure washer

karcher pressure washer being used on concrete - how to use a pressure washer

Get the basics right before you power-wash your car, decking or driveway

Pressure washers are among the most powerful and efficient tools for high-powered cleaning of outdoor spaces and vehicles. They’re also one of the easiest tools to misuse, leading to ineffective cleaning – and perhaps even causing injury or property damage. So, learning how to use a pressure washer correctly is vital.

The Expert Reviews team has tested dozens of pressure washers over the years, and some of us use these devices regularly to clean our vehicles and outdoor spaces. Once you’ve mastered the process, it’s an unbeatable method for making your home sparkle.

In this guide, we’ll take you through the proper process for using a pressure washer, from connecting it to your water and electricity supplies, to washing, depressurisation and storage. The model shown in the step-by-step photos is our favourite all-round pressure washer from market leader, Kärcher: the K4 Power Control.

How pressure washers work

Before you start using your pressure washer, it’s important to understand the fundamentals of how these machines work. Here are some basic principles shared by most pressure washers:

– The pressure washer needs to be connected to a running water supply, such as an outdoor tap. In one hour, a standard pressure washer will use about 400-600 litres of water, which is about three bathfuls. (That’s a lot of water, but a hosepipe can use twice as much in the same period.)

– A pump powered by an electric motor (or combustion engine) pushes an array of plungers up and down inside the pressure washer. The upward strokes of the plungers draw in water from the water source; the downward strokes push water out to the ‘spray gun’ or lance of the pressure washer.

– The pressure washer releases water when you press the trigger on its spray gun or lance.

– Pressure washers often feature a detergent tank, which mixes detergent into the water jet.

READ NEXT: Best Kärcher pressure washers

How to operate a pressure washer

Step 1: Take proper safety precautions

Pressure washers can be dangerous when used incorrectly. Take the following safety precautions before you pull the trigger:

1. Ensure nobody will come into contact with the jet. The high-pressure water can cause cuts, bruises and worse if it hits somebody. Make sure other people and pets are well out of the way before you pull the trigger.

2. Wear protective clothing. PPE-like work boots, gloves and goggles can reduce the severity of injuries if you accidentally come into contact with the water jet or airborne debris.

hand in glove turning on yellow karcher pressure washer - how to use a pressure washer

3. Remove loose materials from the work area. Stones and other small, hard objects can be sent flying by a pressure washer’s jet, leading to a risk of injury or damage.

Step 2: Set up the pressure washer for the intended task

Depending on the range of available pressure settings, you can use a pressure washer to clean a variety of things. These include:

  • Cars
  • Motorbike parts
  • Bicycle frames
  • Driveways
  • Decking
  • Windows
  • Brick walls
  • Stone walls
  • Paint-stripping

A given object or surface will withstand only a certain level of water pressure, before it starts to disintegrate or takes damage. The condition of the surface will also affect an item’s water pressure tolerance. For instance, a cracked tarmac driveway should be cleaned more gently than a driveway that’s in perfect condition.

Usually, you can change a pressure washer’s setting by reconfiguring its attachment(s). For instance, you might twist the nozzle one way to increase the water pressure, and in the opposite direction to decrease it.

Starting pressure (PSI) for common pressure-washing tasks
Car1,500 PSI
Bicycle frame1,500 PSI
Driveway3,000 PSI
Brick wall3,000 PSI
Decking2,600 PSI
Paint removal4,000 PSI (depending on painted surface)

Many pressure washers come with multiple attachments, each designed for specific tasks. Choose the most appropriate attachment for your planned cleaning task, and set the attachment to the best-suited pressure setting (where applicable).

Attach a low-pressure nozzle to the pressure washer if cleaning breakable objects such as a vehicle or window.

Consider using a surface cleaner attachment for pressure-washing the ground.

Use a high-pressure nozzle for the toughest cleaning tasks, such as graffiti removal.

Some pressure washers come with an even wider range of attachments. If you’re in doubt over which attachment to use, consult the instruction manual and use your pressure washer as advised.

It’s a smart bet to start any pressure-washing task using a low-pressure nozzle (or a low setting). This reduces the risk of damage to your property – and you can always increase the pressure if necessary.

Step 3: Connect the pressure washer to water and power

Pressure washers connect via a hosepipe to your household water supply. Find the water inlet on your pressure washer, and connect it securely to a hosepipe using a compatible adapter. Connect the other end of the hosepipe securely to a cold water tap.

hand plugging in pressure washer on concrete - how to use a pressure washer

Now run your pressure washer’s power cable to a mains power outlet (or extension lead) as far away from the work area as you can. Although the pressure washer’s cable should be waterproof, you should avoid trailing it in water, which will pool in low-lying places during pressure washing.

If your pressure washer has a detergent tank, you might choose to equip this with a compatible detergent product that’s suitable for your washing task.

Step 4: Activate and wash

Turn on the cold water tap and switch on the mains power.

When you’re ready to start washing, use the on/activate control on your pressure washer and/or the trigger on its lance to start the water jet. Remember that the jet should be pointing away from you (and other people or animals) at all times.

In terms of washing technique, there are varying best practices for washing different objects and surfaces. Follow the manufacturer’s guidelines on the relevant washing task.

Step 5: Depressurise and store securely

A pressure washer can retain water under high pressure after you’ve finished using it, which can prove hazardous during storage and handling.

karcher pressure washer in key parts on concrete - how to use a pressure washer

So, after turning off the device, it’s important to release any remaining pressurised water from inside it, using the appropriate method for your model of pressure washer. Often, it’s as simple as squeezing a spray gun trigger.

After depressurisation, dry your pressure washer and store it in a safe, dry place that’s inaccessible to children.

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Using additional pressure washer features

The features of your pressure washer will vary depending on the model and make. For example, Kärcher pressure washers are often equipped with a detergent tank that’s designed to accommodate special detergent bottles, which is not the case with most alternative models.

Ultimately, you’ll need to consult your pressure washer’s instruction manual in order to learn how to use any unusual features.

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