What is a pressure washer?
Updated August 2026
A pressure washer is a pump that takes ordinary garden-hose water at about 50 PSI and forces it through a narrow nozzle at 1,300 to 4,000 PSI, so a thin stream does the scrubbing you would otherwise do by hand. Two numbers on the label describe the machine: PSI, the force that breaks dirt loose, and GPM, the gallons per minute that carry it away. Multiply the two and you get cleaning units, the honest way to compare models.
Where it is
This one lives in the garage or shed rather than inside the house, and where you park it matters more than owners expect, since a pump left holding water will crack the first night it freezes. On the machine, find the pump mounted on the front of the motor or engine, the inlet with a small mesh screen where the garden hose attaches, the high-pressure outlet for the steel-braided hose, and the set of color-coded quick-connect tips clipped to the frame or the wand holder.
What it does
The tips do as much work as the pump. Red is a 0-degree pinpoint that gouges wood and can inject water under skin, yellow is 15 degrees for concrete, green is 25 degrees for general washing, white is 40 degrees for siding and cars, and black is the low-pressure soap tip. Match pressure to surface: 500 to 1,200 PSI with a 25 or 40 degree tip on deck boards, 1,300 to 1,600 PSI on vinyl siding held a foot back, and up to 3,000 PSI on a driveway. Too much pressure furs up wood grain, drives water behind lap siding, and strips mortar from brick joints, and none of that shows until everything dries. Electric machines top out near 2,000 PSI and cover cars, patio furniture, and siding; gas machines at 2,500 to 4,000 PSI are for concrete and paint stripping.
Maintenance
Rinse the inlet screen and flush clean water through the pump after every use, then squeeze the trigger with the water off to bleed pressure out of the hose. Before the machine goes into a cold garage, run pump saver antifreeze through it, a 30-second job with an $8 to $12 can. Gas units also want pump oil changed every 100 hours or once a year, stabilized or drained fuel for storage, and a fresh spark plug annually. The pressure washer maintenance checklist and service intervals lay out the season-end routine, which explains why some units reach year ten and others die at three.
What it costs to replace
A replacement pressure washer runs $100–250 for a homeowner electric unit, $300–500 for a mid-range gas unit, or $60–150 for a replacement pump.
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Frequently asked questions
How much PSI do I actually need?
For a typical suburban house, 1,600 to 2,000 PSI at 1.4 to 1.8 GPM handles siding, cars, patio furniture, and light deck cleaning without risking damage. Step up to 2,800 to 3,200 PSI only if you clean bare concrete, strip paint, or wash a long driveway every year. On big jobs, flow matters as much as pressure, because a machine with higher GPM rinses a wider path and finishes a driveway in noticeably less time.
Will a pressure washer damage vinyl siding?
It can, mostly by driving water up behind the courses rather than by cracking the vinyl itself. Use the 40-degree white tip, keep 12 to 18 inches of standoff, hold the wand level or angled slightly down, and work bottom up while soaping and top down while rinsing. Never aim up into lap joints or at window seals. Heavy mildew responds better to a house-wash detergent and a soft brush than to more pressure.
How do I store a pressure washer for winter?
Disconnect the garden hose, run the machine a few seconds to push out standing water, then squeeze the trigger to release pressure. Thread a can of pump saver onto the inlet and run it until foam appears at the outlet. On gas units, either drain the fuel or add stabilizer and run the engine two minutes so treated fuel reaches the carburetor. Store above freezing if possible, because a split pump manifold cannot be repaired and costs more than most electric machines.