Best Generator for Running a Pressure Washer

Electric pressure washers are great for decks, siding, and vehicles, and a generator lets you take one where there are no outdoor outlets, like the back fence or a remote rental property. Pairing the two has one catch. Most electric washers pull 13-15 amps, the maximum for a standard 120V circuit, and their pump motors surge when the trigger is squeezed against a pressurized hose. Here’s how to size the generator, and when a gas pressure washer is simply the better buy.

Electric pressure washer power

Pressure and flow ratings vary with the measurement method, so compare them only within a single brand’s lineup. Power draw is set by the motor, so the amp rating on the label is your best sizing guide.

Generator picks

Best overall for 120V electric washers: 3,000-3,500W

A 3,000-3,500W generator has enough starting capacity for the pump surge, and enough running margin that the motor isn’t starved when you squeeze the trigger after a pause. Inverters are quieter and more fuel-efficient. Open-frame units cost less. Either works, because pressure washer motors aren’t sensitive electronics.

If you already have a 2,000W inverter

Light-duty 1,300-1,600W washers can work on a 2,000W-class inverter, though they may trip on start or after long pauses. Parallel-capable owners can link two units for about 3,200-4,000W of combined running capacity, which comfortably covers a 1,800W washer.

240V commercial washers: 7,500W with an L14-30 outlet

Rare in homes, but common for contractors in noise-restricted areas. These need a generator with 240V output and a matching cord.

Gas pressure washer vs generator plus electric

If you’re buying equipment specifically to pressure wash away from outlets, a gas pressure washer is usually the smarter purchase. It typically delivers 2,700-3,300 PSI at 2.3-2.8 GPM for a similar price to a mid-size generator alone. Generator plus electric washer makes sense when you already own the generator for outage backup, when noise limits favor an inverter, or when you mostly clean cars and patio furniture where lower pressure is safer.

Electrical safety with water everywhere

Most electric pressure washers include a GFCI plug, but using the generator’s GFCI outlet adds a second layer. Keep cord connections off wet pavement. Elevate them on a block or use a weatherproof connector cover. Most washer manuals limit extension cords to 25-50 feet of 12-gauge or 14-gauge wire. For longer reach, add high-pressure hose instead of more cord. Never spray toward the generator, its outlets, or the cord connections.

Trigger pauses and repeated starts

Pressure washers bypass water internally when the trigger is released, which heats the pump. Many have a thermal relief valve or auto-stop. Auto-stop models shut off the motor when you release the trigger, then restart it when you squeeze again. That means repeated starting surges, so the generator must handle frequent starts, not just one. That’s another reason to size at 3,000W or more.

Keep exhaust away from the house you’re cleaning

Washing siding, windows, and decks puts you right up against the house, and the temptation is to set the generator right beside you. Keep it at least 20 feet from the home, with the exhaust pointing away from doors, windows, and dryer or bathroom vents, since open windows will pull exhaust inside. Never run it in a garage, even while washing the garage floor. If the generator also backs up the house during outages, CO alarms inside are essential, and household connections belong on an electrician-installed transfer switch or interlock.

FAQ

What size generator do I need for an 1,800 PSI electric pressure washer?

Plan on about 3,000W. Most 1,800-2,000 PSI electric washers draw 13-14.5A (roughly 1,600-1,800W) with a startup surge of 2,500-3,200W.

Can I use a conventional (non-inverter) generator?

Yes. Pressure washer induction or universal motors run fine on conventional generator power. Choose an inverter for lower noise and fuel use, not for the washer’s sake.

Bottom line

Most 120V electric pressure washers need about a 3,000-3,500W generator, a short heavy cord, and GFCI protection. If you’re buying equipment just for off-grid washing, compare the cost of a gas pressure washer before buying a generator for the job.