How to Clean a Wet and Dry Vacuum So It Keeps Its Suction

Cleaning a wet and dry vacuum comes down to four things: empty the drum, wash or tap out the filter, clear the hose, and dry everything properly before the lid goes back on. Do that after any wet pickup and every few dry jobs, and the machine keeps pulling. Skip it and you get weak suction, a smell that never leaves the garage, and a filter that turns to cardboard.

Before you open it up

Unplug the machine. That sounds obvious, but wet and dry vacs get cleaned in the same five minute window where people are also tidying tools away, and a knocked switch with your hand inside the inlet is not a good day.

Do the job outside or over a bin if you can, because a drum full of plaster dust finds every surface within a metre of wherever you tip it. Gloves are sensible if you have picked up glass or screws, since those settle at the bottom and stay there.

Step 1: empty the drum

Release the catches holding the motor head to the drum and lift it off. Set the head somewhere clean and dry, filter facing up, so you are not resting the intake on grit.

For dry waste, tip the drum straight into a bin bag. For water, most drums have a drain plug near the base, which is far easier than wrestling a full tub. If yours does not, tip it slowly rather than dumping it in one go.

Wipe the inside with a damp cloth. If you have picked up anything organic, or the drum has held standing water for a few days, wash it with warm soapy water and rinse. That smell people complain about is almost always the drum, not the motor.

Step 2: deal with the filter

This is the part that actually controls your suction, and the part most people get wrong. What you do depends on the filter type.

Pleated cartridge filters

Lift it off the cage and tap it firmly against the inside of a bin to knock the bulk of the dust out of the pleats. Then work along the folds with a soft brush, moving down the pleat rather than across it, so you are pushing debris out instead of grinding it further in.

If the filter is rated as washable, rinse it from the clean side outwards with a gentle flow of water. Never blast it with a pressure washer or a jet nozzle. That splits the media and you will not see the damage, you will just wonder why fine dust now blows out of the exhaust.

Foam filters

These are the ones fitted for wet pickup. Wash them in warm soapy water, squeeze them out gently rather than wringing them, and let them dry fully. Foam that goes back damp will smell within days.

Bags and fleece liners

Paper and fleece bags are consumables, not something to clean. Once they are two thirds full the airflow drops noticeably, so change them well before they look packed.

Step 3: clear the hose and wand

Detach the hose from the machine and hold it up at one end. If the far end does not swing freely, or you can feel a lump when you run your hand along it, something is stuck.

Stretch the hose out straight and feed a length of stiff garden hose or a drain rod through it, avoiding anything with a sharp end that could puncture the lining. Once clear, run water through it if it has handled anything wet or sticky, then hang it in a loop rather than coiling it tight so it drains and dries. Check the wand and nozzle openings while you are there, since crevice tools collect a plug of matted debris right at the tip.

Step 4: check the float and the inlet

Inside the motor head there is a float, usually a plastic ball or a sliding collar in a cage, that rises with the water level and shuts off airflow before liquid reaches the motor. Debris jamming that float is a genuine risk to the machine.

Rinse the cage, check the float moves freely up and down, and clear anything wrapped around it. While the head is off, look at the intake grille on the underside and clear any dust matted across it.

Step 5: dry it properly, then reassemble

This step gets rushed constantly. Leave the drum, filter and hose to dry fully in open air. A cartridge filter can take a day or more, and a foam filter is not dry just because the outside feels dry.

Reassemble with the filter seated properly on its cage and the seal sitting flat. A filter that is slightly cocked lets unfiltered air past, which puts dust straight through the motor. Close the catches evenly and store the vacuum with the lid on rather than leaving the drum open.

How often to do all this

• After every wet pickup: drain, rinse the drum, dry the foam filter. No exceptions, this is the one that causes smells.
• Every few dry jobs: empty the drum and tap out the filter.
• After any fine dust job such as plaster, sanding dust or cement: clean the filter the same day, because fine dust packs into the pleats and sets.
• Every few months: full strip, hose check, float check, and a look at the seals.

If suction is still poor after all of that, work backwards through the airflow path. Blocked nozzle, blocked hose, full drum, clogged filter, then a split hose or a perished lid seal letting air in. It is almost always one of those, and almost never the motor.