Many people starting, or even already operating a power washer, or pressure washer business don't think or realize how important it is to have commercial insurance.
Surprisingly, many pressure washer services think (at their own peril) nothing can happen and they are acting safe, so there's no need to have a general liability insurance policy, but if only people that didn't do the right things had accidents, most people wouldn't need insurance for their business. Here's a few court cases where the case actually made it all the way through court and wasn't settled before trial.
For those that may not know, almost all cases get settled before trial, so for every case reaching the conclusion of a court trial, you can bet there's maybe 10 or more court cases that were filed but settled before verdict.
Regardless if your business has a relatively small electric powered pressure unit and your a single operator service, or a company with several crews and many employees with matching vans using gas powered pressure units with multiple connections, if you're a power washing contractor, you certainly have some risk to other's property that you may want general liability coverage for. Risks often never considered include slip and falls, and accidents from the water stream.
White v Pajak, 1992 in Harford Connecticut - An important pressure washer case where an insurance exclusion clause was the bain to a homeowner and power washer contractor alike. In this case, the homeowner alleged the power washer, Edward P. d/b/a Harford Pressure Wash damaged the plaintiff's siding on his home. The Power washer had a commercial business insurance policy, underwritten by National Casualty Company. National Casualty had an exclusion that went along the lines of "to property damage to work performed by or on behalf of the named insured arising out of the work or any portion thereof or out of materials, parts or equipment furnished in connection therewith."
Bowles v. Weld Tire & Wheel, Inc. 2001 in Missouri - A contractor using a gas powered pressure washer was sued because the plaintiff exposure to carbon monoxide while the defendant pressure washer business operated the gas machine in an enclosed area. This case was even appealed and lost.
Grinnell v. St. Francis Med. Ctr., Inc. 2013 in Louisiana – There wasn't a power washer contractor, but the principle remains the same. The plaintiff slipped and fell due to a wet walking surface.
I'm going to add more cases (I found hundreds)
Finally, if you're about to start or already have a power washer business, make sure you not only have commercial insurance, but complete coverage. As you can see above (and you should also look up the court cases), power washing contractors face lawsuits and if you're sued, you're likely out of business from the lawyer fees alone if you have assets a lawyer feels they can get access to.