Guide · Couplers, adapters and swivels
Pressure washer fitting types explained
Each joint on a pressure washer can use its own standard: M22, 3/8 or 1/4 in quick-connect, pipe thread, a brand bayonet or garden-hose thread.
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Short answer
A pressure washer is a chain of connections: water inlet, pump outlet, both hose ends, gun inlet, gun to wand, and wand to nozzle. Each joint can use a different standard, such as M22, a 3/8 or 1/4 in quick-connect, a pipe thread, a brand bayonet or garden-hose thread. Name the standard at each joint before you buy a part.
The connection chain
Start at the faucet and follow the water:
- Water inlet: a garden hose joins the machine on the low-pressure side.
- Pump outlet: the high-pressure hose starts here.
- Hose ends: one end at the pump, one at the gun. They need not match each other.
- Gun inlet and outlet: the gun takes the hose and passes water to the wand.
- Wand to nozzle: the nozzle or attachment clips on at the end.
A part fits only if both of its ends match the joints on either side. A hose with the right pump end and the wrong gun end does not fit.
M22 threaded fittings
In the name M22, the M means metric and 22 is the outside thread diameter in millimeters.[1] The full thread is M22 x 1.5, a 1.5 mm pitch; Westinghouse labels its 14 mm adapter "M22x1.5 - 14mm".[2][3] M22 also comes with a 14 mm or 15 mm inner stem, which is a separate choice: see M22 14 mm vs 15 mm.
Quick-connect plugs and couplers
A quick-connect has a male plug and a female coupler with a sliding collar. Champion's 100386 manual is a clear example of one machine using two systems:
- The pump outlet has a female quick connector with a sliding metal collar that takes the hose's male end, and the parts list names a 3/8 quick coupler.[4]
- At the other end, the hose is a female collar connector that takes a male fitting on the gun, and the wand joins the gun with an M22 coupler.[4]
See the Champion 100386 page for the full chain.
Some machines are M22 almost end to end. Active Products says the Active 2.0 uses M22-14 mm hose and gun connections and a lance with a 1/4 in quick-connect outlet.[5]
Quick-connects come in sizes. The 3/8 in and 1/4 in sizes do not interchange: see 3/8 vs 1/4 in quick-connects.
Pipe threads on guns
Commercial guns often use tapered pipe threads instead of M22. Suttner lists most of its spray guns with a 3/8 in FPT inlet and a 1/4 in FPT outlet, each model with its own maximum PSI and GPM.[6]
Pipe threads come in families. NPT is tapered with a 60-degree thread angle; BSPT is tapered and BSPP parallel, both at 55 degrees.[2] Tapered pipe threads seal on the threads and need a sealant, while straight threads seal with a gasket or O-ring and need none.[2] More in NPT, BSP and M22.
Brand fittings
Some makers use their own interfaces. Kärcher's bayonet gun kit uses a Kärcher-specific quick connect for the high-pressure hose and a Kärcher bayonet connection for spray wands.[7] These are neither M22 nor a 1/4 in quick-connect. See the Kärcher bayonet page.
Garden-hose thread at the inlet
Dixon lists 3/4 in garden hose thread as 1.0625 in male outside diameter with 11-1/2 threads per inch.[8] This is the low-pressure side.
Kärcher's 2.645-221.0 is a garden hose quick connect set for the water inlet, and Kärcher says it cannot be used on the high-pressure outlet.[9] The kit has three pieces: a garden-hose connector, an inlet connector for Kärcher electric washers, and a connector that converts the threaded inlet on Kärcher gas washers to quick connect.[9]
Adapters bridge two standards
Adapters often have a different interface at each end. MTM Hydro, for example, sells an M22 14 mm plug by 3/8 in quick-connect coupler.[10] Some kits cover several joints at once: RYOBI's RY31QCK01 is a 7-piece quick-connect kit rated for washers up to 4,000 PSI that links the garden hose to the inlet, the pressure hose to the pump outlet and the hose to the trigger handle.[11]
| Joint | Common standards | Where a maker documents it |
|---|---|---|
| Water inlet | Garden-hose thread; brand quick connect | Kärcher 2.645-221.0 (inlet only) |
| Pump outlet | M22; 3/8 in QC; brand QC | Champion 100386 (3/8 QC coupler) |
| Hose ends | M22 14 or 15 mm; 3/8 in QC; brand QC | Flexzilla (M22, 14 mm stem) |
| Gun inlet | M22; QC; 3/8 in FPT | Suttner (3/8 FPT) |
| Gun to wand | M22; 1/4 in FPT; Kärcher bayonet | Champion 100386 (M22 coupler) |
| Wand to nozzle | 1/4 in QC; brand fitting | Active 2.0 (1/4 in QC) |
Each standard has its own page with the parts whose maker states it: M22 14 mm, M22 15 mm, 3/8 in quick-connect, 1/4 in quick-connect, NPT, BSP, garden-hose thread and the Kärcher bayonet.
Parts by joint
Picks that fit2 products
For a pump outlet and gun that both take a 3/8 in quick-connect, choose the SIMPSON Monster Hose 41028 (3/8 in x 50 ft, 3/8 in QC plug and socket, 4,500 PSI, cold water to 140°F).
More on choosing
The Westinghouse kit is sold for Westinghouse machines: confirm Westinghouse lists your model and read each piece's ends before buying. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or the brand.
3/8 in quick-connect hose for cold water
SIMPSON Monster Hose 41028 3/8 in x 50 ft 4,500 PSI cold-water pressure washer hose, 3/8 in QC
Westinghouse's larger quick-connect kit
Westinghouse WPWFIT3KIT 6‑piece quick-connect kit for garden hose and M22‑14 mm hose/gun, brass
SIMPSON states the 41028's 3/8 in plug and socket ends, 4,500 PSI and 140°F cold-water rating.[12]
Next
Questions
What size fittings are on a pressure washer?
There is no single size. The water inlet, pump outlet, hose ends, gun, wand and nozzle are separate joints, and each can use M22, a quick-connect, a pipe thread, a brand fitting or garden-hose thread. Read your manual joint by joint.[4]
Are pressure washer fittings universal?
No. Each joint has its own standard, and even M22 comes with a 14 mm or 15 mm stem. Name the standard on both ends of any part you buy.[1]
What is the difference between M22 and quick-connect?
M22 is a metric thread you screw together. A quick-connect is a plug pushed into a coupler and held by a sliding collar. Champion's 100386 uses a quick-connect at the pump outlet and an M22 coupler at the wand.[1][4]
Can I use a garden-hose quick connect on the high-pressure side?
Not the Kärcher kit: Kärcher says its 2.645-221.0 garden-hose quick connect set is for the water inlet and cannot be used on the high-pressure outlet.[9]