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How to use a pressure washer

Updated: 21.10.2026

The washer is out of the box, the outdoor tap is on the wall, and you are not sure which hose goes where. Learning how to use a pressure washer is a sequence: people and pets clear, water connected, air bled, then the motor. Run it backwards and you can spin a pump dry, or leave a machine full of water for the first frost. This page does not rank the eleven listings. Specs stay on our [pressure washer comparison](/hub/compressors/pressure-washer). We used public UK guidance and published manuals, not a garden lab test. A qualifying purchase through our links can earn a commission at no extra cost to you.

The washer is out of the box, the outdoor tap is on the wall, and you are not sure which hose goes where.

Our top picks

Kärcher Kärcher K 2 Horizontal

Best overall

Kärcher Kärcher K 2 Horizontal
7.6/10about £69.12
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Kärcher Kärcher K 4 Power Control Flex

Alternative

Kärcher Kärcher K 4 Power Control Flex
6.7/10about £188
View offer
Bosch Bosch UniversalAquatak 135

Rank 3

Bosch Bosch UniversalAquatak 135
8.1/10about £108
View offer
On this page
  1. 1.Before you pull the trigger
  2. 2.Connect the water, then the power
  3. 3.Clear the air before you switch on
  4. 4.Wash, stop, and store

Before you pull the trigger

Walk the area first. Move pots, toys and the car if the car is not today's job. Children, pets and bare feet stay out of the spray. Wear glasses. Electrical Safety First's advice is a UK plug, an RCD outdoors, the cable out of the puddle, and no spraying of sockets. Do not stand on a ladder. The jet will push you. If the lead or the plug is split, stop. Connect the water before the switch. A long evening can become a statutory nuisance under the Environmental Protection Act 1990.

Connect the water, then the power

Fit the inlet hose to the tap and to the machine. The high-pressure hose runs from the pump to the gun: 3 m on the K 2 rows, 7 m on the UniversalAquatak 135, 8 m on the K 4. Do not confuse it with a garden hose you may still have to buy. A VYTRONIX reviewer had to supply that feed hose. Seat the couplings, then tug them. Fit a wide fan first, not the dirt blaster. Open the tap fully. Kärcher's home FAQ limits inlet water to 40°C on the machines that page covers. Do not copy that limit onto the ETOOLAB listing, which does not state it. Lay the cable where the jet will not cut it. Only then does the plug go into an RCD-protected socket. The motor stays off until the air is out.
Kärcher Kärcher K 2 Horizontal

Testsieger

Kärcher Kärcher K 2 Horizontal
7.6/10about £69.12
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Clear the air before you switch on

With the motor off and the tap open, squeeze the trigger until the stream is a solid column. UK Kärcher support at Core Service describes that start, and the manual in your box wins if it differs. STIHL's UK note says the same: flood the gun with the motor off. They also call a backflow preventer legally required under the Water Supply (Water Fittings) Regulations 1999. WaterSafe's plain version is an approved double check valve. Do not leave the hose in a bucket, a pond or a drain. When the stream is steady, release the trigger, switch on, and start on the fan. Running dry can damage the pump. A kinked K 3 or K 4 hose will also kill the flow. Kärcher Outlet asks for a 13 A extension lead no longer than 10 m, uncoiled. If the RCD trips as you switch on, unplug and stop.

Wash, stop, and store

Keep the lance moving. A stationary jet stripes timber, lifts paint and digs a joint. Distance for a car is on the pressure washer for cars page. Joints and decking are on the pressure washer for a patio or driveway page. A Temporary Use Ban can stop mains washing of a private car, a path or a patio. Ofwat cites a fine up to £1,000. Read your water company's notice. A water butt is not automatically exempt. Shut down in reverse: motor off, trigger squeezed, then the tap closed. Disconnect the hoses and drain the pump before a frost. Kärcher Outlet's winter note is to store the machine where it will not freeze. Stop and use a dealer if the cable is damaged, the RCD trips at once, oil would enter a drain, or the stone is old and untested.

Common questions

Do I turn the tap on before the motor?
Yes. Open the tap, bleed the air with the motor off until the stream is solid, and only then switch on. Starting against a closed tap is the dry run support desks tell you to avoid.
Why is there no pressure the first time?
Usually air in a dry hose, or a tap that is only half open. Hold the trigger with the motor off until the water runs as a steady column. A kink in a K 3 or K 4 hose looks like a dead pump, so walk the hose flat first.
Can I test it with no water?
No. A dry test is how a pump gets damaged, according to Kärcher's UK support steps. Even a quick listen needs the tap open and water at the lance.
How do I pack it away for winter?
Switch off, release the pressure, close the tap, disconnect both hoses and drain the pump the way the manual shows. Store it where it will not freeze. Leaving it full in an unheated shed is how casings split.
What socket should I use?
A UK three-pin socket protected by an RCD, with the cable away from the water and the jet. If you need a lead, Kärcher Outlet asks for a 13 A lead no longer than 10 m, uncoiled. Do not reset a tripped RCD while you are standing in the puddle.
Can I use it during a hosepipe ban?
Only if your water company's notice allows it. A Temporary Use Ban can cover a private car, a path and a patio washed from the mains. Ofwat cites a fine up to £1,000. A water butt is not an automatic exemption.
When should I stop and not DIY the repair?
Stop if the cable or plug is damaged, the RCD trips as soon as you switch on, or water is coming out of the motor housing. Also stop if oil would run into a drain, or if the stone is historic and untested. Opening the pump is a dealer job.

Related pages

Pressure washer buying guide

Pressure washer

Best pressure washer UK for cars, patios and bikes

Pressure washer for cars without marking the paint

Pressure washer for patio slabs, joints and decking

Sources

Public UK sources, Bosch DIY UK and the Kärcher FAQ below. amazon.co.uk listings checked on 19 October 2026.

  1. legislation.gov.uk: Water Supply (Water Fittings) Regulations 1999, Schedule 2 (retrieved 19 October 2026)
  2. legislation.gov.uk: temporary use bans (retrieved 19 October 2026)
  3. Ofwat: hosepipe bans and non-essential use bans (retrieved 19 October 2026)
  4. Electrical Safety First: pressure washers (retrieved 19 October 2026)
  5. BSI: BS EN 60335-2-79 high-pressure cleaners (retrieved 19 October 2026)
  6. Bosch DIY UK: pressure washers (retrieved 19 October 2026)
  7. Kärcher: FAQ on suction from a water butt (retrieved 19 October 2026)
  8. WaterSafe: backflow from hosepipes (retrieved 19 October 2026)