Home-How » 10 Reasons Why Shop Vac May Be Blowing Dust (Fixed!!!)

10 Reasons Why Shop Vac May Be Blowing Dust (Fixed!!!)

Shop vacs are extremely helpful when it comes to cleaning up a workspace, garage, and wet messes in basements or even outside. Things get a bit less convenient, however, when your shop vac starts spouting out dirt instead of picking it up.

If you’re wondering, “Why is my shop vac blowing dust? Is it broken?” don’t worry – there are at least eight other reasons your shop vac may be blowing dust, and most of them are easily fixed.

Analyzing Your Shop Vac

Before you figure out what’s wrong with your shop vac, we’re going to go over a few of its most important parts including different filters that you should become familiar with.

  • Motor cover assembly: is the top part of your vacuum (often a gray or black plastic). This part holds the motor of the appliance.
  • Cartridge filter: is used across industries and uses a cartridge within a casing to catch small particles, chemicals, and pollutants.
  • HEPA filter: stands for a high-efficiency particulate air filter. This type of filter removes 99.97% of tiny pollen, dander, sawdust, drywall dust, bacteria, mold, fine debris, and airborne particles.
  • Foam sleeve filter: can be used alone to clean up wet messes. This sleeve is usually 8” in diameter and 6.5” high. This is best used for cleaning wet messes.
  • Reusable dry filter: is also called a non-disposable filter. It can be made of different materials and can be washed with soap and water instead of being replaced completely.
  • Collection Bag: is used to pick up fine dust. It’s an optional bag you can put in your tank to make it easier to clean out.
  • Fine dust bag: is similar to a collection bag, and you can find some that are HEPA-rated
  • Filter levels:
    1. General
    2. Medium
    3. Fine

Analyzing Your Shop Vac

Why Your Shop Vac May Be Blowing Dust

Your shop vac should be cleaning up a mess, not spewing a mess out at you. It’s time to troubleshoot and find out which of these nine reasons is the cause of your rebellious vacuum’s behavior.

1. You’ve Chosen the Wrong Setting

Different companies make shop vacs, but the structure of the appliance is usually similar across brands. Shop vacs can be used as vacuums as well as air blowers.

Some shop vacs have two settings: one for vacuuming and one for blowing. These should be easily distinguishable near the power button of your appliance.

Sometimes the wrong button is pressed by accident or someone else uses your shop vac and forgets to change the setting back to vacuum. Always double-check this setting before turning on your machine.

2. The Hose Is Connected to Wrong

If your setting is correct and you notice dust blowing out of your machine, not from the hose, you’ve likely placed the hose in the wrong outlet. In many vacuums, the front holds the inlet port that sucks up materials, whereas the back park has the exhaust port that blows out materials.

If you notice that your hose isn’t sucking air and instead air is coming out of the exhaust port, you’ll need to turn off your machine. Check your settings and then remove your hose and insert it into the exhaust port. The hose should now blow clean air.

3. The Drum Is Full

The drum or tank of your shop vac is where all of the collected particles are stored. This drum may be filled with a collection or dust bag or be empty. Either way, it will have to be emptied once it’s full or the particles could make their way back into the airflow and come out of the machine.

A sure sign that your tank is full is when your shop vac has weak suction power. The hose may even leave behind dirt while vacuuming.

If your shop vac has liquid waste, first unplug the unit. Press both side tabs and remove the tank cover, followed by the hose. Take the tank to a drain where you can dump it out and clean it.

Rinse out the hose by running water through it. Then, remove the filter sleeve and rinse it out as well. Dry the components and then put them back together.

Why Your Shop Vac May Be Blowing Dust

4. You Don’t Use a Collection Bag

Collection bags are not necessary for shop vacs, but they are useful for many reasons. Firstly, they make cleanup a breeze as you don’t need to hand wash the tank after use.

Second, they will stop loose dust from circulating back into your room, especially if you are using a low-grade filter that doesn’t trap the smallest particles.

5. The Filter Is Damaged

Your shop vac’s filter is the primary factor in trapping dust, pollen, and small debris within your vacuum. If the filter is ripped, has a hole in it, or is otherwise damaged, the dirt will pass straight through it and return to the machine’s air circulation.

To check your filter, first, unplug your shop vac. Then, remove the covering lid. The top piece of this lid should have the filter attached.

Look for the filter tabs on the side of the filter and pull the filter up while the main part remains fixed. Examine your filter and replace it with a new one if you notice it is damaged. Most disposable filters should be changed every 3-6 months depending on use.

6. The Filter Needs to Be Cleaned

All shop vac filters can be cleaned, so long as it’s done properly and the filter is fully dry before being reinstated in the vacuum. Your disposable and reusable filters can be removed and washed to ensure a longer filter life and a cleaner vacuum system.

First, go outside and knock the dust loose on the inside of a trash bin, as dust particles tend to fly in the air. You may want to wear work gloves during this process. You can also use compressed air or a separate vacuum to loosen the particles on the filter.

Next, wash the filter in warm soapy water. You can do this in a bucket or sink. Paper filters are finer than reusable filters, so use lighter water and air pressure while cleaning them.

Finally, let the filter dry for a few hours, preferably in the sun. Only insert the filter back in when it’s completely dry.

The Filter Needs to Be Cleaned

7. The Filter Is Installed Wrong

If you put the filter in incorrectly or purchase the wrong size, it could fall into the basin or cause an obstruction. A filter that looks squished or sunken should be removed and checked for size. Reinstall the filter correctly, and try to use your shop vac again.

8. Your Filter Needs to Be Upgraded

In the first section of this guide, we analyzed the different filters that come with most shop vacs. If you’ve stuck to the standard paper filter that comes with most shop vacs upon purchase, you might have noticed that it gets fuller quicker, rips easier, or isn’t as easy to clean as you thought; now may be the optimal time to upgrade your filter to prevent more dust from blowing out of your shop vac.

Some of the best options include HEPA filters and reusable dry filters. If you don’t use a container or dust bag already, consider adding it to your vacuum to keep things neat and prolong your filter’s life.

9. The Hose Is Clogged

While this doesn’t happen as often, the hose of the shop vac can get debris trapped in it, slowly spewing out dirt and particles if you try to blow air out of the vacuum. You can usually see a large blockage by peaking in the hose when the shop vac is off.

To fix a blockage, you can use a regular vacuum hose cleaner, such as the one in the video below, run the hose under warm water, or hit the sides of the hose with force while the machine is off.

10. Your Shop Vac Is Broken

If you have tested out all of the other potential causes on this list and still have trouble with your shop vac blowing out dust, your machine may have a mechanical issue. Shop vacs can last anywhere from five years to forty years depending on the brand, how often you use them, and how well-maintained it is.


Dealing with a shop vac malfunction can quickly spread debris and dust around your home, causing a mess. If, after checking all of these potential causes, your shop vac continues to blow dust, it may be time to consider replacing your machine altogether. Most of the time, however, you’ll be able to get to the root of the problem by adjusting the filter or hose or emptying the drum.


1. Can You Use a Shop Vac Without a Filter Bag?

You can use a shop vac without a filter bag. But adding a filter bag will make cleanup easier and help prevent your filter from getting clogged.

2. Can You Use a Shop Vac Without the Paper Filter?

Your shop vac needs a filter to capture debris that flows into the machine. You can choose between a paper filter, HEPA filter, or reusable filter, among others.

3. Should the Filter Be Removed When Vacuuming Water with a Shop Vac?

All filters should be removed and replaced with a foam sleeve when vacuuming water with a shop vac. The foam sleeve filters out water that is sucked into the machine.

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