Pressure Washer Fitting & Adapter Finder

Both fittings share an identical outer thread diameter of 22mm (M22 × 1.5 pitch), meaning they will easily screw together by hand. However, the internal brass male stem (pin) measures either 14.0mm or 15.0mm. Connecting an M22-15mm female hose to an M22-14mm male pump leaves a 1.0mm unsealed gap around the rubber O-ring, which immediately results in high-pressure water spraying everywhere. Most residential brands (Ryobi, Greenworks, Simpson) use 14mm, while Sun Joe and select AR Blue Clean models use 15mm. See our engineering teardown on M22 14mm vs 15mm Fittings for caliper measurements and leak fixes.

Sun Joe electric pressure washers use an M22-15mm pump outlet and hose fitting, whereas almost all aftermarket high-pressure hoses, short stubby guns, and extension wands are built to the commercial M22-14mm standard. A dedicated Sun Joe pressure washer hose adapter converts Sun Joe's 15mm female collar to a standard 14mm male stem, allowing you to run standard commercial hoses and stubby guns without leaks or blown O-rings.

There are two primary high-pressure pressure washer quick connect sizes: 1/4" QC and 3/8" QC. The 1/4" quick connect format (0.465" plug diameter) is universal for the discharge end of trigger guns, lances, foam cannons, and colored spray tips (0° to 40°). The 3/8" quick connect format (0.585" plug diameter) is designed for high water volume lines, including high-pressure hoses, pump discharge ports, and commercial spray gun inlets.

To convert pressure washer hose to quick connect fittings, you need an M22-to-3/8" conversion kit. Install a 3/8" quick-connect brass socket onto your pump's threaded M22 outlet. Thread a 3/8" steel plug onto the pump end of your hose, a 3/8" brass socket onto the gun end of your hose, and a 3/8" plug into the base of your spray gun. Once installed, your entire setup connects and disconnects in seconds with zero hand wrenching. For flexible hose recommendations, check out our engineering Uberflex Hose Review. If your high-pressure line has developed a blowout or pinhole leak near the crimp collar, read our step-by-step tutorial on how to fix a pressure washer hose.

In the battle of NPT vs GHT pressure washer threads, the difference is thread taper and seal mechanics. Garden Hose Thread (GHT) is a straight, non-tapered 11.5 TPI thread that seals strictly by compressing a flat rubber washer inside the female coupling. National Pipe Taper (NPT) is a tapered thread (14 or 18 TPI) that seals by metal-to-metal wedge deformation and requires Teflon tape or anaerobic paste. Never force a GHT hose fitting directly onto an NPT pipe nipple; use a brass GHT-to-NPT adapter.

The standard pressure washer o ring replacement size depends on the coupler: 1/4" quick-connect sockets use an AS568-011 O-ring (5/16" ID × 1/16" cross-section), while 3/8" quick-connect sockets use an AS568-110 O-ring (3/8" ID × 3/32" cross-section). For M22 male stem pins, standard size is 14mm × 2.5mm (or 15mm × 2.5mm for Sun Joe). Always choose 90A Durometer Nitrile (Buna-N) or Viton O-rings to resist high pressure and chemical degreasers.

A quick-connect coupler blowing off under load indicates that the sliding outer collar did not snap fully forward over the stainless steel ball bearings. Always pull backward on the accessory after inserting it to confirm the locking balls have fully seated in the plug's groove. If the collar fails to slide forward, the internal O-ring may be swollen from harsh chemicals, or debris is lodged inside the socket.