Pressure Washer Basics

Article by Mark Trotta

When it comes to cleaning driveways and sidewalks, pressure washing can't be beat. It's also great for cleaning decks, stairways, fences, and patios, as well as the exterior of your house. Attach a foam cannon, and it's safe to clean your car, truck, or motorcycle.

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Pressure washers use a high-pressure water spray, which is generated from a small engine into a pressure pump. Their power rating is measured in PSI (pounds of pressure per square inch). The GPM figure is how many gallons of water per minute they can move.

Gas vs Electric Pressure Washers

For any serious amount of cleaning, you want a gas-powered pressure washer. They have greater PSI and GPM's than electric versions. The extra power means that you can tackle bigger jobs and get quicker results. Since they're not dependant on a power source, gas-powered units are more portable, making them better suited for hard-to-reach areas.

pressure washer power ratings

What PSI Do I Need?

The PSI that you will need will depend on what the surface is that you're trying to clean. For hard surfaces like cement, brick, stone, and steel, you'll need 2500 to 3000 PSI. For softer substances like wood decks or aluminum siding, you don't need or want any more than 1200 to 1500 PSI.

Nozzle Sizes

The physical size of the nozzles are the same, but the spray patterns are different. Pressure washer nozzles are conveniently color coded.

pressure washer nozzles

Spray Nozzle Colors

Red: A red tip is the narrowest angle. It gives a pure water stream, which means at high pressure, it can do a lot of damage. Don't use a red-tipped nozzle up close on any surface.

White: If you're cleaning your house exterior, a white-tipped nozzle is good for windows and siding. Unlike the red nozzle that has a zero degree spray, a white tip gives a 40-degree spray.

Green: A green tip has a 25-degree spray. Because it disperses water over a wider area and with less force, it's good for softer surfaces and a lower psi, such patio furniture, wood decks, and stucco finishes. It also works well for washing your car or truck.

Black: With a spray angle of 65 degrees, the black nozzle is the widest and gentlest. It's basically a strong mist, so it won't really remove dirt or stains, It's best suited for making surfaces wet.

Yellow: The yellow tip has a 15-degree angle. This works well on cement walks and driveways.

Getting Set Up

First, clear away any items that may be in your path before starting the pressure washing process. Attach a hose to the back of the pressure washer, then turn the water on, then start the machine.

Until you gain a little experience, hold the wand with both hands so that it won't get away from you. Keep the spray tip approximately 18 inches away from the surface you're cleaning to minimize the risk of damage.

Pressure Washing Concrete

Supplies needed to pressure wash a severely dirty concrete driveway, walkway, or patio, are a cleaning solution specially formulated for use on concrete, and optionally a stiff scrubbing brush. To best clean concrete, use a power washer with a pressure rating of at least 3000 psi and a flow rate of at least 4 gallons per minute.

After 20-30 minutes, you find a "zone" where you can work comfortably and repeatedly. For my cement driveway, I used a yellow nozzle. For the wood patio deck, I used a green nozzle.

pressure wash concrete before and after pictures

Concrete sidewalk before and after pressure washing.

How Much Gas Will I Need?

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My Craftsman pressure washer is powered by a 7-horsepower Briggs engine. Maximum PSI is 2700. A tankful of gas is good for an hour or so.

Foam Cannon

Here's a great tool to add to your cleaning arsenal. If you intend to pressure wash your car, truck, motorcycle, or boat, play it safe and get a foam cannon. All you need to do is put liquid soap in the bottle and turn the knob. You can use anywhere from 10:1 mix to 50/50 mix of soap and water.

pressure wash with foam cannon

Shop: Foam Cannon

Wand Upgrade

If you're looking to replace a wand or upgrade one from a cheaper pressure washer, replacement wands and nozzles are inexpensive and are compatible with almost gas-powered and electric pressure washers.

pressure washing basics

Shop: Pressure Washer Replacement Wand and Nozzles

Clogged Nozzle

Once, after several minutes of work, I noticed the spray wasn't coming out as strong as it had been. My first thought was lack of water pressure, so I checked the water spigot and it was open all the way. Then I noticed the metal wand was warm to the touch, which it wasn't before (and it shouldn't be). It turned out to be a clogged nozzle. I don't know of a way to clean them, so I swapped out the tip to the next closest spray angle (yellow to green).

TIP: Wrap male connections of hose with Teflon tape to avoid leaks.

Aside from cleaning my driveway and sidewalk every year and stripping the wood deck every now and then, my pressure washer doesn't see much use. Because it does not get run often, it is a prime candidate for gas going bad.

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Cautions And Disclaimers

Pressure washers can spray water at 3,000 PSI. That's powerful enough to damage wood surfaces of your deck, vinyl sidings and windows. To avoid property damage and personal harm, always be aware of where the wand is pointing.

The high pressure of the water means that debris and water will spray back toward you. Use caution. For any pressure washing job, at least wear eye protection, and you may want to wear hearing protection as well.