Wet/dry vacs are perfect for the workshop, shed or garage. Outshining the common canister vacuum, they boast enough power to vacuum heavy debris as well as liquids without clogging or leaking. Choosing a wet/dry vac depends on what you plan to use it for. Among those factors, consider whether or not a cordless version may be better suited to your working environment or if power is more important to you.
'''Horsepower''' (HP) is what determines the strength and the speed of a given model. Note that power also correlates with noise levels. Remember that the listed HP is usually "peak HP," in other words, the maximum HP the model can reach. It doesn't always give an adequate representation of how well the vacuum will run for an entire job.
'''Tank capacity''' (one to 20 gallons) should be taken into consideration when you know you will be cleaning up large spills. If you expect to use the vac more for dry debris and dust, skimp on tank capacity and invest the money in a higher HP model.
* Portable models (two gallon capacity or less) are usually outperformed by small and large models because they simply lack power.
** Peak of 1.5 HP, which is fine for light jobs or as a supplement to a larger vac.
** Inexpensive choice -- prices start at $20 for a portable one gallon vac..
* Small models have a bit more power (two to six HP) and capacity (six to eight gallons).
** Portable and easier to maneuver and store. They also make less noise than their larger counterparts.
** Smaller capacity means more trips to empty the tank. This can be a hassle.
** Good performance at lower costs make these an attractive buy. They come with more attachments than a portable model.
* Medium size models (10 to 14 gallon capacity and three to five HP) are strong, convenient and stable.
* Large models are the loudest but also the most powerful options available.
** Large 16 to 20 gallon capacity with a whopping six HP on the majority of models.
** A challenge to move and store.
** A strong build gives them long-term durability and reliability.
** Most attachments are standard features on larger models.
'''Noise''' is measured in decibels. Many wet/dry vacs are very loud. You should wear ear protection at noise levels of 75 decibels or more. Depending on where you plan to use the vacuum, noise might be an important factor in your purchasing decision.
'''Price''' is not a direct predictor of vacuum efficacy but it does indicate whether you will get certain niceties (less noise, a good dust filter). More expensive vacuums will have these and probably more. They also excel at dust collection, which may be important if you do work with materials that produce very fine dust.
Just because a vacuum is more expensive does not mean that it will include a full complement of accessories. Check the specifications so that you know exactly what tools come with your vac.
* '''Drain Spout''' -- Makes emptying the tank much easier on large models because you don't have to lift and tilt to pour out the waste.
* '''Filters''' -- Like house vacuums, wet/dry vacs produce fine dust particles. Those with allergies should invest in high-efficiency filters. Cartridge filters are the most convenient since they don't require much maintenance; the two-piece paper/foam filters, where you have to remove the paper for vacuuming up liquids, are also easy to use.
** Filter Shaker -- A filter shaker will clean the filter without opening the machine.
** Filter Door -- Some models allow you to remove the filter without opening the main canister.
* '''Hose Size -'''- Wider (2.25" to 2.5") is better if you need the vacuum to suck up large debris like wood chips and nails.
** For fine dust collection, or if you want to attach your vacuum to your power tools, you might need a smaller hose (and an adapter kit).
* '''Hose Extension -'''- Makes you stoop less, but keep in mind that a longer hose has less suction compared to a shorter hose on the same vacuum.
* '''Hose Lock''' -- Keeps the hose from detaching if you pull the vac from the hose.
* '''Long Cord -'''- Depending on the size of the space you work in, a long power cord can make the vacuum easier to maneuver.
* '''Multi-purpose models''' -- Some offer the ability to act as a leaf blower. This secondary action may not be up to par with a dedicated leaf blower's performance but can be useful for the occasional or light clean up on porches, decks or driveways.
* '''Nozzles -'''- Rubber squeegees are a really helpful attachment to have for cleaning up liquids quickly.
* '''Onboard Attachment Caddy -'''- Helps keep tools organized and within reach.
* '''Mobility''' -- Wheels and a wide, stable base will make moving your vac easier.
** Big handles on top make carrying a large wet/dry vac up and down stairs easier.