There are cleanup jobs that require just a scrub brush and elbow grease. Then there are the really tough ones, such as removing layers of dirt from a concrete sidewalk or mildew from a wooden deck, that only a pressure washer can handle.

* Need to know: A pressure washer takes water from an outdoor faucet through a hose and focuses a high-pressure stream on whatever you're trying to clean. How much pressure you need depends on which jobs you plan to do.

For light-duty jobs such as washing a car or cleaning aluminum or vinyl siding or patio furniture, a washer with 1,300 to 2,000 pounds per square inch of pressure (psi) is enough. A medium-duty washer (2,000 to 2,600 psi) will dislodge dirt from a concrete sidewalk. Heavy-duty washers run from 2,600 to 4,000 psi, and are for stripping paint or removing stains from a concrete driveway.

* Power points: Electric power washers typically produce up to 1,500 psi, only enough for lighter jobs. To avoid electric shocks, have an electrician install a ground-fault circuit interrupter on the outdoor outlet into which you'll plug the power washer; the GFCI will cut off the electricity if the power cord comes into contact with water. (As a general safety rule, all outdoor electrical outlets should have GFCIs.)

Medium- and heavy-duty washers typically are gasoline-powered, with 5- or 6-horsepower engines. They require the same kind of maintenance as gasoline-powered lawn mowers: You'll need to clean the air filter and change the spark plug and oil.

* What it will cost: Power washers can cost $100 to $2,000, depending on type and whether they are electric or powered by gasoline. Electric units cost $100 to $250. Gas-powered washers start at $250 and go up to about $2,000 for commercial models.

* Bad advice: "Buying a pressure washer is more cost-effective than renting one." Most people need a pressure washer once or twice a year, if that often. It might be better to rent a washer for $50 to $75 a day to clean your deck, brick patio or sidewalk than to spend $200 for something that just takes up space in the garage or basement.

* Good advice: Don't pressure-wash deteriorating stucco. The slightest pressure may further loosen the material, and water may get behind the stucco and seep into interior walls, putting your house at risk for mold development.

Some pressure-washing jobs -- really big ones and high jobs come to mind -- are better left to professionals. Never use a power washer while standing on a ladder unless a second person is available to help, making sure the ladder is stabilized and the hose from the washer doesn't get tangled. Power washers, even light-duty ones, have a kick to them.