A handyman can pressure wash in California as long as they have a contractors license that requires 4 years of journeyman experience.
And some states have specialist pressure washer licenses that are required.
I've known a few handymen that pressured washed some driveways in California without a license and they never had an issue but you could get into trouble without the license.
Be sure to always turn the hose on or water on before starting the pressure washer as running the pressure washer without water can and will damage the pressure washer pump and lead to the pressure washer pump seizing up.
It does hurt to start a pressure washer without water as starting a pressure washer without water can damage the pump and seals and components.
Always turn the water on and then start the pressure washer to avoid damage to the pump and components.
Also if not using the pressure washer within a minute or so you should shut the pressure washer off.
Operating a pressure washer without water can cause the pressure washer pump to overheat and seize up.
The difference between a pressure washer and a power washer is a power washes uses heat and pressure to clean things and a pressure washer uses only cold water at high pressure to wash things.
Other than the difference in temperature used the pressure washer and power washer are the same thing but one uses heat and the other doesn't.
Pressure washing is usually less expensive than power washing because it uses less water and isn't as intense as power washing.
Power washers are better for large jobs, while pressure washing is more suited to smaller tasks.
In inexperienced hands, a pressure washer can cause damage to homes or even to your car's paint, trim, or delicate parts.
High-pressure water can strip away protective coatings and even force water into vulnerable areas, leading to rust or electrical issues.
Pressure washers are incredibly strong, and can break skin and cause other injuries.
A pressure washer should never be used on any living thing—no humans, pets, or plants.
Don't use a pressure washer while working on a ladder or on your roof—the recoil could throw you off balance.
Vinyl siding can withstand a powerful gas pressure washer (2,500-3,000 psi).
Aluminum, stucco or soft-grain wood homes will do better with a less powerful washer (about 1,200-1,500 psi).