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What Is a Wet-Dry Vacuum?

Tom Raley
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An essential tool in any shop is a wet-dry vacuum. This vacuum, often referred to as a shop-vac, offers versatility and convenience every do-it-yourself-er craves. Broken down to the most basic elements, the wet-dry vac is nothing more than a vacuum cleaner at heart.

Its design, however, enables it to accomplish more, in more environments than any other vacuum. Once you have a wet-dry vac you will never be without one again.

Unique Features of the Wet-Dry Vac

The most unique feature of the wet-dry vac is its versatility. It provides powerful suction which picks up nails, screws and other pieces of debris which would destroy other vacuums. It can also vacuum in a wet environment just as well as a dry one. The vacuum can be used to remove a fine layer of dust, or empty a basin of water. While wet-dry vacs come in many sizes, the most popular will have up to a 10-gallon capacity. This large capacity allows you to clean up a great many small messes, or one large one.

How It Works

The wet-dry vac consists of three major components. The bucket, or collection chamber, the motor unit and the hose. The motor sits atop the collection chamber and drives a fan which draws air through the collection chamber and hose. As the air passes into a smaller area (the hose) it increases in speed and creates suction. This allows it to pick up the particles and carries them to the collection chamber. As the air enters the larger collection chamber the air slows down and the particles are released. The air is then vented out the upper portion of the vacuum.


Some wet-dry vacs serve a dual purpose. When the air is vented out of the vacuum it is done so through a small opening in the upper portion of the unit. On these models you can disconnect the hose from the vacuum side and plug it into the exhaust port and create a strong blower. Tip: If your hose ever becomes clogged with large debris, unplug it from the vacuum and plug it into the exhaust port. Then place the other end of the hose in the vacuum side. When you turn on the unit the air will force the clog out of the hose and into the collection chamber.

Safety in Wet Environment

The reason the wet-dry vacuum can pick up both wet and dry materials is that the materials never pass through any electrical or mechanical components. The motor unit is separate from the collection chamber to prevent any potential for electrical shock. While the motor is safe from water exposure, the power cords you use to bring electrical power to the unit are not. It is highly recommended you use a GFCI (Ground Fault Circuit Interrupter) equipped extension cord when using a wet-dry vacuum. A GFCI constantly checks for ground faults and if one is found cuts off all electrical power. While a GFCI cannot prevent electric shocks, it will normally prevent them from being fatal.

Wet-Dry Vacuum Cost

When you go shopping for a wet-dry vac you will find you have a wide selection both in size and power. A smaller unit with a six- gallon collection chamber and a 3.0 h.p. motor will cost approximately $50. This is a good size to have around the garage for small household tasks. You can step up to a unit with a 5.5 h.p. motor and 14-gallon collection chamber for around $100. This is a good size for the more serious workshop. If you need a bit more power you can get a 6.5 h.p. unit for $50 more. On the other end of the spectrum is the 1-gallon, 1.0 h.p. model. Good to keep in your car, kitchen or utility room. This unit will cost in the neighborhood of $30.