Best wet/dry shop vacuum

How to choose

Ignore peak horsepower and the gallons on the box

Peak horsepower is a lab figure, and DeWalt's own page says motors don't run at that level in actual use.²¹ Project Farm measured the current drawn by seven vacs labeled 5.5 to 6.5 peak horsepower and worked out about 1.3 to 1.8 horsepower.⁸ The label didn't predict results either: a DeWalt rated at 6 peak beat all three 6.5 peak vacs on suction and on picking up sand.⁸

The gallons on the box describe the drum, not what it holds in use.^{1 22} When Project Farm filled those vacs until they stopped, 16-gallon drums held 12.2 to 13.9 gallons, 14-gallon drums 9.5 to 11.6, and one 12-gallon drum 9.4.⁸

Compare airflow and water lift, from the same test

Airflow, in cubic feet per minute (CFM), moves light, bulky debris such as sawdust and leaves. Water lift, in inches, pulls up heavy or embedded debris. You want a balance, because strong suction with weak airflow clogs easily on dry debris, and the reverse struggles with heavy objects.¹⁴ Maker ratings run differently from lab figures, so only compare numbers from the same test.⁷

Buy a wide hose for dry debris

Hose width is the easiest thing to check in a store. On GearLab's dry debris test, the 2 1/2-inch hose vacs took 35 to 66 seconds, and the Stanley 6-gallon with its 1 1/4-inch hose took 135.²³ A narrow hose matters less for water: that Stanley took 14 seconds on GearLab's wet test, against 6 to 11 for the big vacs.²³ If you'll pick up wood chips, leaves or drywall scraps, buy 2 1/2 inches.

Size the tank for your back, and buy a drain

Water weighs about 8.3 pounds a gallon.¹³ Expect a 12-gallon vac to stop at around 9 to 10 gallons, which is about 80 pounds of water before you count the vac.^{8 13} Ridgid's manual says not to lift a vac that's heavy with liquid, and to scoop or drain it first, so a drain is close to essential on anything over about 6 gallons.⁴ One owner argues for 5 gallons or less for water, because a full big tank is too heavy.²⁴ That's reasonable if you have stairs and no floor drain.

Pick the filter for the job

Ridgid's manual says not to vacuum drywall dust or cold fireplace ash with a standard filter, because they can pass through and blow back into the air. Use a fine dust filter, and expect to clean it often.^{4 7}

For water, Ridgid says you can leave the paper filter in for small amounts, under 2 inches in the drum, but should swap to a foam filter for larger jobs.²⁵ One owner says a filter used on wet messes will grow mold, so dry everything after a water job.²⁶

If you have a lot of drywall to sand, attach a vacuum sander. NIOSH compared five vacuum sanding systems with ordinary sanding in 1994, and exposures fell 80 to 97 percent.²⁷ Drywall dust can cause lasting throat and airway irritation, and silica in some compounds adds a risk of silicosis and lung cancer, so wear a respirator as well.²⁷

Don't use a shop vac for lead paint dust

A HEPA filter doesn't make a shop vac a HEPA vacuum. EPA's lead rule for renovation firms requires a vacuum designed so that all the air leaves through a filter that captures 99.97% of 0.3 micron particles, with none leaking past it.⁵ EPA advises against a shop vac fitted with a HEPA filter, because a retrofit isn't necessarily sealed.⁵ Ridgid also says its HEPA filter alone doesn't guarantee HEPA filtration from the vac.²⁸ If you'll disturb lead paint, treat these picks as unsuitable, and get a vacuum built as a HEPA vacuum.

Stay safe around flood water

Electricity comes first. Have an electrician check the house before the power goes back on, and run a shop vac only if you have power and an electrician has found it safe. Wear rubber boots, and never turn the power on or off or use an electric tool or appliance while you stand in water.⁶ Don't touch electrical equipment that's wet, and plug the vac into a properly grounded outlet.^{4 29} If you'd have to step into standing water to reach the main switch, call an electrician to turn it off.⁶

Flood water can carry sewage. Children, pregnant people, and people with weakened immune systems or chronic breathing problems such as asthma should stay out of the cleanup.²⁹ Everyone else needs an N-95 respirator, goggles, gloves, long sleeves, long pants and boots.²⁹ EPA also says the job may be too hard or dangerous for you, so consider a professional.²⁹

A wet vac doesn't finish the job. Use one only while materials are still wet, because otherwise it may spread mold spores, and clean and dry the tank and hose afterward.³⁰ Try to clean and dry the home within 24 to 48 hours, but don't run fans if you can already see mold.²⁹

Keep it away from anything that can burn

Sparks inside the motor can ignite vapors or dust, so don't use a shop vac near gasoline, lighter fluid, cleaners or oil-based paint. Never vacuum anything burning or smoking, including hot ash. Empty the drum after each use, because rags or sawdust with stain or urethane on them can ignite on their own. If the float shuts off the suction, stop and empty the drum.⁴

Wear ear protection on long jobs

These machines run loud, at 84 to 102 dB across GearLab's 10 vacs, so wear earplugs or muffs for anything longer than a quick cleanup.²³

How many you need

One per household is enough. A 5 to 6 gallon vac suits spills and car cleanup, and 9 to 12 gallons suits basements and big projects. If you have no garage, basement or yard, a cordless stick or handheld vacuum may do, but never use a household vacuum on water.²