How to Use a Shop Vac for Water

a shop vacuum sitting on the garage floor
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Project Overview
  • Working Time: 10 mins
  • Total Time: 20 mins
  • Yield: Clean up water, 10-foot square area
  • Skill Level: Beginner

A wet/dry shop vacuum is indispensable around the home. Despite the name, a shop vacuum's utility extends far beyond the workshop since it tackles messes that ordinary household vacuums cannot handle.

A shop vacuum's ability to suck up water saves you from using towels to soak up water on the floor or trying to squeegee it away. A shop vacuum even acts as a pump to remove larger quantities of water standing in a tub, shower, pool, aquarium, or garden pond.

What's the Best Type of Wet/Dry Vacuum to Buy?

Wet/dry vacuums range in capacity from 1 gallon up to 20 gallons, with most vacuums in the 4- to 10-gallon capacity range.

A few inches of water in a tub or water spread out across a wide area will quickly fill up smaller vacuums. The amount of water in carpeting is difficult to estimate because the water is not visible. With water soaking into the fibers and the padding, carpeting can hold as much as 1 gallon per square foot.

If you want to vacuum up large quantities of water, a higher capacity wet/dry vacuum is helpful to avoid frequently pouring out the canister. At the same time, large canisters full of water are heavy and unwieldy. With water weighing close to 8 1/2 pounds per gallon, full wet/dry vacuums on the higher end of the moderate capacity range weigh as much as 130 pounds.

Using a Wet/Dry Vacuum With Water

Estimate amount of water

Plug into a GFCI outlet

Remove bag

Remove dry filter (wet filters are fine)

Be aware of the quantity of water in the canister

Dispose of water properly

Clean and dry canister and accessories

What You'll Need

Equipment / Tools

  • 1 Wet/Dry Vacuum


  • Wet filter


  1. Remove the Bag

    During wet operation, wet/dry vacuums never use collection bags. Unlatch the top, blower-unit section of the vacuum. Remove the collection bag and any fasteners and set it aside.

  2. Change or Remove the Filters

    Since they are made of paper, dry filters are never used during the wet operation. In some cases, they are plastic units with attached pleated paper folds. Or they might be filter cloths that wrap around the filter unit, secured with a rubber band. If the wet/dry shop vacuum has a wet filter, replace the dry filter with the wet filter.

  3. Attach the Wet Nozzle

    Wet/dry vacuums come with a variety of nozzles. One nozzle with a broad, flat head is designated a wet nozzle, though other nozzles usually will work for water, too. The wet nozzle works well for flat surfaces.

  4. Plug Into a GFCI Outlet

    Because vacuuming water mixes water with electricity, it is recommended that you plug the vacuum into a GFCI outlet. Most wet/dry vacuums are double-insulated, which means that you can plug them into non-GFCI outlets if you wish.

  5. Vacuum the Water

    For Water Spread Across a Floor

    Turn on the vacuum. Place the nozzle on top of the water. Hold it in place until the water under and around it is depleted. Progressively move the nozzle to a new section until all of the water is gone.

    For Large Quantities of Standing Water

    Turn on the vacuum and place the nozzle on top of the water. Wet/dry vacuums can vacuum up large quantities of standing water very quickly. One way to know if the canister is full: the motor sound changes, indicating this its speed has changed.


    The more extensions you add to the hose, the more difficult it is to pick up water. Avoid using the extension wand, if possible.

  6. Filter Out the Debris

    Open the vacuum canister. Before pouring out the water, remove any large pieces of debris.

  7. Safely Dispose of the Water

    Pour the water into a proper disposal area. Water with construction debris should not be poured into garden beds.

  8. Clean and Disinfect the Canister and Accessories

    Because wet/dry vacuums mix water with organisms, there is a high potential for mold and mildew growth inside the canister after use.

    Clean out the canister first with fresh water. Then pour 1 gallon of warm water with 1/4 cup of household chlorine bleach, thoroughly cleaning all areas of the canister. Run the water through the hose. Turn the canister upside-down and let it dry out. Hang the hose vertically so that it drains out. Store the vacuum and parts only after they are completely dry.