Electric or gas pressure washer: PSI, GPM and nozzles explained

A pressure washer strips grime from concrete, decks and siding far faster than scrubbing. Choosing one is mainly about two numbers and being honest about what you'll clean.

PSI and GPM

• PSI (pounds per square inch) is how hard the water hits. Higher PSI removes stubborn dirt.
• GPM (gallons per minute) is how much water flows. Higher GPM rinses debris away faster.

Some people multiply them (PSI × GPM) to compare overall cleaning power. A machine with high PSI but low GPM can feel slow, because it takes longer to rinse a surface clean.

Electric vs. gas

	Electric	Gas
Typical power	Lower; suits cars, patio furniture, small decks and patios	Higher; suits large driveways, decks and heavy grime
Noise	Quieter	Loud
Maintenance	Little	Oil, fuel, winterizing
Starting	Push button or trigger	Pull start
Portability	Light; needs an outlet	Heavier; goes anywhere

For most homeowners with a car, a patio and some furniture, an electric pressure washer is enough. Large driveways and heavy-duty cleaning favor gas.

The nozzle color code

Most pressure washers use quick-connect nozzles with a standard color code:

Color	Spray angle	Use
Red	0°	Pinpoint; very aggressive. Rarely needed; can damage surfaces and cause injury
Yellow	15°	Stripping stubborn grime on concrete
Green	25°	General cleaning of decks, patios, cars at a distance
White	40°	Gentle cleaning: cars, windows, siding
Black	65° (low pressure)	Applying soap and detergent

Start with a wider nozzle and keep a distance, then move closer only if needed.

Avoid damage

• Wood decks can splinter and gouge with high pressure or narrow nozzles; use wide angles and keep moving.
• Siding can let water behind it if you spray upward into seams.
• Cars: use the white or green nozzle at a distance; avoid spraying directly at seals and trim.
• Never point the spray at people, pets or yourself. Pressurized water can cause serious injuries.

Useful accessories

• Surface cleaner: a spinning attachment that cleans driveways and patios evenly without stripes.
• Longer hose and extension wand for second-story areas.
• Foam cannon for car washing.
• Hose reel for storage.

Questions people ask

What PSI do I need to clean a driveway?

Higher PSI and GPM make driveways faster. Many electric models handle light cleaning; heavy stains and large driveways favor gas models and a surface cleaner.

Can I use any soap in a pressure washer?

Use detergents made for pressure washers. Some household cleaners can damage pumps or harm plants.

How do I store a pressure washer for winter?

Drain water from the pump and hoses, and follow the manufacturer's winterizing steps, often including a pump protector product, to prevent freeze damage.