What Adapter For

How to connect a garden hose to a pressure washer

Your garden hose screws onto the pressure washer’s water inlet, hand-tight (some machines include a short inlet adapter). On the high-pressure side, many machines use M22 fittings, which come in 14 mm and 15 mm versions.

What fits

Usually no adapter. The garden hose screws onto the pressure washer’s water inlet

the inlet takes 3/4" garden hose thread

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M22 pressure washer hose adapters, 14mm and 15mm

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  • On Generac’s 3500 psi model, the water inlet is where you “Connect garden hose here”. Tighten it by hand and use a hose no longer than 50 feet. Some machines need a short adapter on the inlet and come with it. Kärcher’s K1800PS includes an “adapter for 3/4" garden hose”.
  • The high-pressure side is different. The hose from the machine to the spray gun uses M22 fittings on many machines (Kärcher’s K1800PS lists “standard M22 hose connections”), and M22 comes in 14 mm and 15 mm versions. Sun Joe sells a 14 mm to 15 mm adapter for its SPX washers. Check your manual for which one you have.
  • Any hose or fitting on the high-pressure side must be rated for the machine. A replacement high-pressure hose’s rating “MUST exceed” the machine’s maximum pressure.

The inlet takes a garden hose. On the high-pressure outlet, fittings differ by brand (Kärcher’s European K-series use a click-in Quick Connect) and every part must be rated for the machine’s pressure.

Common questions

What is the difference between M22 14mm and 15mm?

Both use the same M22 thread, but a 14mm part and a 15mm part need an adapter to join: Sun Joe sells a 14mm M22 male to 15mm M22 female adapter for its SPX washers. Your manual says which one your machine uses.

Keep going

Connect two garden hosesHose thread vs pipe threadAdapter finderGarden hose to 1/2" pipeGarden hose to 3/4" pipeGarden hose to drip irrigationConnect different drip tubing

For a different part on either end, open the adapter finder with this pair picked.

Where we get our information from

The sizes on this page come from published standards and the makers’ own documents. Checked against published data from Generac, Kärcher and Sun Joe.

See all 3 sources
  • Generac, pressure washer owner’s manual (model 1540-0)
  • Kärcher, K1800PS pressure washer and Quick Connect high-pressure hose
  • Sun Joe, SPX-M22M2F 14mm M22 male to 15mm M22 female adapter

General guidance from manufacturer and standards data. Parts vary by brand, so check the size printed on the package against what you measured. For gas lines or anything inside a wall, use a licensed plumber.