Pressure Washer Fittings

Every fitting you need to plumb a rig lives in this collection: quick connects, M22 adapters, hose barbs, plugs, and caps in brass, steel, stainless, and poly. Sun Brite Supply has been outfitting pressure washing rigs from our Gaithersburg, MD counter for over 30 years, and matching a mystery fitting is a daily event here. Stuck on one? Call 301-519-9274 or bring it in and we will thread it to the right part on the spot.

How to Identify Pressure Washer Fittings

Most fitting orders go wrong at identification, not selection. High pressure gear in the US uses a short list of connections. M22 is the threaded collar with an internal o-ring seat found on many consumer and prosumer machines. 3/8 inch NPT is the tapered pipe thread on pumps, unloaders, and hose ends. Quick connects come in 1/4 inch for nozzles and 3/8 inch for hoses and guns. Garden hose thread handles the supply side. Measure before you order, because M22 and 22mm-looking BSP parts will start on the same threads and then leak forever.

Quick Connect Couplers: Which End Gets What

The convention that keeps water off your boots: couplers face downstream, plugs face upstream. Put the female coupler on the pump outlet and the hose ends, and put plugs on guns, lances, and accessories. Do it that way and everything on the truck snaps to everything else. Nozzles run the smaller 1/4 inch system while hoses and guns run 3/8 inch, and the two do not interchange. A quad coupler on the lance keeps four nozzle tips within reach so you stop digging through the truck for the white tip.

Brass, Plated Steel, Stainless, or Poly

Brass is the workhorse. It machines clean, resists corrosion, and costs little, so it should be your default on the high pressure side. Plated steel plugs and hex plugs cost less and give their life to rust eventually, which is fine for parts you treat as disposable. Stainless earns its premium wherever chemicals flow, on soft wash rigs, and on hot water machines where brass dezincifies faster. On the low pressure tank side, Banjo poly fittings, cam lever couplers, and line strainers handle bleach and surfactants that would eat metal, and they weigh nothing. Match the metal to the liquid and the fitting outlasts the hose.

Finding and Fixing Leaks

A drip at a connection is almost never the fitting. It is the o-ring. Pull the plug, pick out the flattened ring, and press in a new one. Ten seconds, ten cents. Use thread sealant or tape on NPT threads only, never on quick connect plugs or M22 collars, because those seal on the o-ring and tape just gums the works. Hot water machines cook standard o-rings early, so spec high temp rings there, and keep a tub of spares on the truck. A crew that stops for one o-ring run burns more money in drive time than a lifetime supply of rings costs.

Fitting Lookup by Job

Sizes and stock shift week to week. Call and we will confirm the exact thread before you order.

From the Field

What the counter sells tells you where rigs fail. O-rings and quick connect plugs outsell every other fitting ten to one, because they are the parts that wear while everything else just sits there. Our standing advice: build a fittings bin for the truck with spare plugs, couplers, o-rings, a few hex plugs, and thread sealant. Twenty dollars of parts prevents the 40 mile drive that kills a Saturday. Second lesson from returns: half the M22 fittings that come back were the wrong internal size. Gas machines usually run the 14mm seat and electrics run 15mm, and they look identical until water sprays sideways. Check the machine, not the box.

Related Categories

• Quick connects and quick connect tips
• Brass pipe fittings
• Stainless steel pipe fittings and steel pipe fittings
• Poly fittings for chemical plumbing
• Hose barbs, adapters, elbows, and tees
• Swivels to stop hose twist at the gun
• Hose fittings and garden hose couplings for the supply side
• Near DC or Baltimore? Our Gaithersburg store matches mystery fittings in person

Frequently Asked Questions

How do I know what size fittings my pressure washer uses?

Look at the gun and hose ends. A large threaded collar with an o-ring inside is M22. A smooth sleeve that pulls back is a quick connect, 1/4 inch on nozzles and 3/8 inch on hoses. Tapered threads on the pump are usually 3/8 inch NPT.

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

The outside looks the same but the internal seat differs. Gas machines typically use a 14mm seat and electric machines use 15mm. Mixing them gives you a connection that threads on and leaks anyway.

Are pressure washer quick connect fittings universal?

Within a size, mostly yes. Any 3/8 inch plug fits any 3/8 inch coupler regardless of brand. The 1/4 inch nozzle system and the 3/8 inch hose system do not mix with each other.

Should I buy brass or stainless steel fittings?

Brass for general high pressure plumbing, stainless where bleach and strong chemicals flow or on hot water rigs. Poly fittings own the low pressure chemical side because nothing in a soft wash mix bothers them.

Why does my pressure washer leak at the connections?

Nine times out of ten it is a flattened or nicked o-ring, not the fitting. Replace the ring first. If the leak is at an NPT joint, reseal the threads. Only then blame the metal.

Do I need Teflon tape on pressure washer fittings?

Only on NPT pipe threads. Quick connects and M22 collars seal on o-rings, and tape on those joints does nothing but shed bits into your nozzle.

Can standard fittings handle hot water machines?

The metal can, the o-rings often cannot. Hot water units run near 200 degrees, so use high temp o-rings and prefer stainless or brass over plated steel. Ask us when you order and we will spec the right seals.