How to Choose a Foam Cannon for Your Pressure Washer

On this page (10 sections)

1. Quick answer: how to match a foam cannon to your washer
2. Connector and fittings
3. Bottle size and wide-mouth fill
4. Orifice size and flow
5. Dial, fan and foam control
6. Materials and build
7. Common mistakes when you choose a foam cannon
8. Does your washer already include a foam cannon?
9. Soap type and cleaning
10. Pick a foam cannon for your pressure washer by buyer type

To choose a foam cannon for your pressure washer, match three things: the connector on your gun or wand, the bottle size you need, and the flow and pressure your washer puts out.

The two connectors this guide covers are the 1/4 inch quick connect and the M22 fitting, so check your gun or wand for one of those first.

This is a decision guide, not a ranked list, because the right cannon depends on your washer. If you're new to washing a car at home, start with Pressure Washer for Car: The Complete Home Wash Guide, then come back here for the cannon.

Quick answer: how to match a foam cannon to your washer

Start with the gun or wand you already own, because the cannon has to attach to it. Then check these four points in order, and fix any one that doesn't fit before you move on.

1. Connector: the cannon's fitting has to match your gun or wand, usually a 1/4 inch quick connect or an M22 fitting.
2. Bottle size: pick a bottle that holds enough mix for the cars you wash in one session.
3. Flow and pressure: the cannon's maker should allow your washer's flow and pressure, so compare both sets of numbers.
4. Dial and fan: look for a knob that sets the foam mix and a nozzle you can adjust.

Connector and fittings

The connector decides whether a cannon attaches at all, so check it before you compare anything else. Your gun or wand has one fitting, and the cannon has to match it, or you need an adapter to join the two.

To find yours, look at the end of the gun or wand and check the manual. A quick connect has a collar that slides back to release the cannon, and an M22 fitting screws on.

Pressure washer foam cannon fittings: 1/4 inch quick connect

The Tool Daily Foam Cannon has a 1/4 inch quick connect inlet. Tool Daily says it must connect to a standard 1/4 inch quick connect pressure washer gun or wand, and that it is made for a pressure washer, not a garden hose or faucet.

If your gun has a 1/4 inch quick connect, you can narrow the search to cannons with that fitting. Check the fitting on your gun rather than guessing from its shape.

M22 fittings

Westinghouse says its ePX3050 is compatible with accessories such as surface cleaners, undercarriage cleaners and foam cannons with M22 fittings.

If your gun or wand uses M22, look for a cannon with that fitting, or an adapter that joins the two sizes. For the exact accessory list, check Westinghouse's website or the washer's manual.

For more on fitting sizes and adapters, see Foam Cannon Fittings: Quick Connect, Adapters, Orifice.

Bottle size and wide-mouth fill

Pick a bottle that matches how many cars you wash in one session. A bigger bottle means fewer refills, but it weighs more when it's full.

A full liter of liquid weighs about 2 pounds, and that weight hangs off the end of your gun or wand.

The Tool Daily holds 1 liter (0.22 gallon) and the Big Mouth Max holds 34 ounces, which is about the same, so bottle size alone won't separate them.

Wide-mouth fill

Chemical Guys says the large fill opening on the Big Mouth Max prevents spills and makes adding soap quick. It also says the 34 ounce bottle holds enough solution for multiple washes.

A wide mouth matters most when you pour soap straight from a jug, because a narrow neck is harder to pour into without spilling.

Confirm the Big Mouth Max's connector against your gun or wand before you order, since the fitting decides whether it attaches.

Orifice size and flow

The orifice is the small opening inside the cannon that the water passes through, and its size affects how much water and pressure the cannon needs. Neither cannon in this guide gives an orifice size, so ask the maker if you need that number.

Flow matters because a cannon needs enough water moving through it to foam. A washer that puts out less flow than the cannon expects can give thin foam, even with good soap.

Flow and pressure: what electric washers put out

Flow is the volume of water your washer puts out, measured in GPM. Pressure is the force of the spray, measured in PSI.

Here are the figures for the washers and the cannon in this guide:

• The Westinghouse ePX3050 makes 2100 max PSI and 1.76 max GPM, with 1800 rated PSI and 1.2 rated GPM.
• The Greenworks 2100 PSI makes 2100 PSI at 1.2 GPM.
• The Tool Daily cannon has a 3000 PSI maximum operating pressure.

The max figure is the highest number a washer can reach, and the rated figure is the level it's built to run at. For everyday use, plan around the rated numbers.

Both washers stay under the Tool Daily's 3000 PSI limit, so pressure isn't the worry here. Flow is the number to check: read the cannon maker's flow requirement, if it gives one, and compare it with your washer's rated GPM.

Dial, fan and foam control

A knob that sets the foam mix and an adjustable nozzle give you the most control at the cannon, so look for both before you buy.

The Tool Daily's top knob and nozzle

Tool Daily says turning the top knob right, toward the minus sign, gives the thickest mixture. It also says to adjust the nozzle until you get a spray pattern you like.

In plain terms, the knob controls how rich the foam is, and the nozzle controls how wide it sprays.

The Big Mouth Max's adjustable nozzle

Chemical Guys says the adjustable nozzle and air injection system make thick foam that clings to surfaces.

Set the nozzle, then spray a small, low panel first to see how the foam looks before you work across the rest of the car.

Nozzle tips and fan angle

The Tool Daily comes with five nozzle tips at 0, 15, 25, 40 and 65 degrees. The 0 and 15 degree tips are narrow, so keep them off painted surfaces.

A 25 or 40 degree fan is the usual starting point, since a wider fan spreads the spray over more area. The washer maker's instructions set how far the tip should sit from the car.

Chipped, peeling, loose or poorly repainted paint can be damaged by a pressure washer, so check the paint before you spray.

Materials and build

Plastic keeps a cannon light, and metal fittings suit a cannon you connect and disconnect often. Brass and stainless steel are the usual metals for the fittings, because that's the part that gets screwed and unscrewed.

Plastic body

The Tool Daily has a plastic exterior. At 150 grams, or about 5.3 ounces, it adds very little weight to the end of your wand.

Stainless steel fittings and seals

Chemical Guys says the Big Mouth Max has stainless steel fittings and durable seals that support reliable performance and long service life.

It weighs 12.3 ounces, more than twice the Tool Daily's weight, so expect a heavier feel at the end of the wand.

Common mistakes when you choose a foam cannon

Skipping the connector check is the costly mistake, so do that first. The other errors are easy to avoid once you know them.

• Buying by bottle size alone. The Tool Daily and the Big Mouth Max hold about the same amount, so size won't decide between them.
• Connecting it to a garden hose. Tool Daily says its cannon is made for a pressure washer, not a garden hose or faucet.
• Using a narrow tip on paint. The 0 and 15 degree tips are narrow, so start with a 25 or 40 degree fan.
• Mixing chemicals. Use car wash soap as the label says, and keep chemicals out of the cannon.

If a cannon doesn't fit your gun, don't force it. Use an adapter that matches both ends, and check that it suits your washer's pressure.

Does your washer already include a foam cannon?

The Westinghouse ePX3050 comes with a foam cannon, while the Greenworks 2100 PSI comes with a soap applicator instead. If you want a cannon in the box, the Westinghouse is the simpler choice.

Westinghouse ePX3050

The ePX3050 makes 2100 max PSI and 1.76 max GPM, with 1800 rated PSI and 1.2 rated GPM. The box includes a foam cannon, a gun, a wand and three quick connect nozzles at 15 degrees, 25 degrees and turbo.

It has a 20-foot hose and a 35-foot GFCI power cord, and Westinghouse backs it with a 3 year limited warranty. Follow the maker's manual for setting up the power cord.

Greenworks 2100 PSI

The Greenworks 2100 PSI makes 2100 PSI at 1.2 GPM, and it comes with a soap applicator rather than a foam cannon.

It uses a 1/4 inch universal quick connect system, so a cannon with a 1/4 inch quick connect is the one to look for.

Greenworks says it suits medium-duty cleaning tasks, and that there's no gas, oil or spark plug to service. It weighs 22 pounds and starts with a push button.

Both washers top out at 2100 PSI, but the ePX3050 reaches 1.76 max GPM against the Greenworks' 1.2 GPM.

For more washers that work with a cannon, see Best Pressure Washers With a Foam Cannon for Cars.

Soap type and cleaning

Use car wash soap, mix it as the label says, and never put chemicals in a cannon. Soap and water are all the bottle should hold.

Soap and warm water

Tool Daily says to fill the bottle with soap and warm water to get thick foam. Start with the mix ratio on the soap label, then adjust the foam with the top knob.

Foam Cannon Dilution Ratio: How Much Soap to Use covers the amounts.

Fill the bottle before you attach the cannon to the gun or wand, so you can see the level and close the cap cleanly.

Keep chemicals out of the bottle

Never mix chemicals in the bottle. If your car has a ceramic coating, follow the coating maker's advice on soap and foam before you use a cannon.

Cleaning the cannon after use

Rinse the bottle and fittings with clean water after each wash, so soap doesn't dry inside them. Empty any leftover mix before you store the cannon.

If the foam turns thin later, a clogged nozzle is a common cause, and Foam Cannon Not Foaming: Causes and Fixes lists the usual fixes.

For the wash steps once the cannon is filled and connected, see How to Use a Foam Cannon on a Car.

Pick a foam cannon for your pressure washer by buyer type

Pick the Tool Daily if you already own a 1/4 inch quick connect gun, the Big Mouth Max if you want a wide fill opening, and the Westinghouse ePX3050 if you want a cannon included.

The Greenworks 2100 PSI fits buyers who want a quick connect washer and plan to add a cannon separately.

You already own a 1/4 inch quick connect gun

The Tool Daily suits this buyer. It's plastic and light at 150 grams, and Tool Daily says it suits washing cars, motorcycles, trucks and SUVs.

You want a wide fill and metal fittings

The Big Mouth Max suits this buyer. It has a wide fill opening, a 34 ounce bottle and an adjustable nozzle, and Chemical Guys says its fittings are stainless steel.

Check its connector against your gun before you order.

You want a washer that comes with a cannon

The Westinghouse ePX3050 suits this buyer. It comes with a foam cannon, makes 2100 max PSI, and carries a 3 year limited warranty from Westinghouse.

If you plan to swap in another cannon later, check that its fitting matches the connector on the washer's gun.

You want a quick connect washer and will add a cannon

The Greenworks 2100 PSI suits this buyer. It runs at 2100 PSI and 1.2 GPM, uses a 1/4 inch universal quick connect, and starts with a push button.

Pair it with a 1/4 inch quick connect cannon, and confirm the cannon's flow requirement with its maker.

If your gun uses a fitting that matches neither cannon here, look for an adapter first. Then check the cannon's flow requirement with its maker before you buy.

Still deciding between a cannon and a hose gun? Foam Cannon vs Foam Gun: Which Is Better for Cars? compares the two.

Frequently asked questions

What foam cannon works with my pressure washer?

Start with the fitting on your gun or wand, because the cannon has to attach to it. A 1/4 inch quick connect cannon, like the Tool Daily, fits a gun or wand with that fitting, and Westinghouse says its ePX3050 accepts foam cannons with M22 fittings.

Is a bigger foam cannon bottle better?

Not always, because a bigger bottle means fewer refills but more weight at the end of your wand when it is full. The Tool Daily holds 1 liter and the Chemical Guys Big Mouth Max holds 34 ounces, so size alone won't separate them.

Does an electric pressure washer have enough flow for a foam cannon?

Some do, since the Westinghouse ePX3050 comes with a cannon and is rated at 1.2 GPM, with 1.76 GPM at most. For a separate cannon, check the maker's flow requirement against your washer's rated GPM, and ask the maker if it gives no number.

Brass or plastic foam cannon?

Plastic keeps a cannon light, like the 150 gram Tool Daily, while brass or stainless steel fittings suit a cannon you connect and disconnect often. Chemical Guys says the Big Mouth Max has stainless steel fittings and durable seals, but the connector size still decides whether any cannon attaches.