The short answerMost garages do well with a 9 to 12 gal wet/dry vac with a 1-7/8 or 2-1/2 in hose, for $90 to $160. For cars and small messes, a 2.5 to 5 gal model at $50 to $90 is enough. Ignore peak HP.
What to buy
Cars and small messes
2.5 to 5 gal portable wet/dry vac
Light enough to carry in one hand, and it stores on a shelf. The small tank fills fast with water, and the narrow hose clogs on big debris.
$50 to $90
See options on Amazon →Most garages
9 to 12 gal with a 1-7/8 or 2-1/2 in hose
Enough tank and airflow for sawdust, car cleaning and a leaking water heater. It takes up floor space and it's loud.
$90 to $160
See options on Amazon →Flooded basements and big shops
14 to 16 gal with a drain port and a 2-1/2 in hose
Holds a lot of water and swallows wood chips and leaves. It's bulky, and a full tank is too heavy to lift, so the drain port matters.
$150 to $250
See options on Amazon →Add-on for drywall and fine dust
Fine-dust cartridge filter and collection bags
Standard filters let fine dust blow back into the room. A fine-dust filter and a bag trap it, and they need replacing as they clog.
$15 to $40
See options on Amazon →Links go to Amazon. As an Amazon Associate we earn from qualifying purchases.
For serious flooding, rent a pump or a water extractor, which move far more water than a vac. For everything else, a shop vac is cheap enough to own.
What the numbers mean
- Gallons
- Tank size. Water weighs about 8 lb a gallon, so a full 16 gal tank is over 130 lb.
- Peak HP
- A lab number measured for an instant, with no real work being done. A household outlet can't supply 6 HP, so ignore it.
- CFM
- Cubic feet per minute, the amount of air the vac moves. More CFM picks up light, bulky debris like sawdust and leaves faster.
- Water lift
- Suction strength, also called sealed pressure, measured in inches. Higher numbers pull water and heavy bits like screws and gravel.
- Hose diameter
- 1-1/4 in clogs on wood chips and leaves, and 1-7/8 in is a good middle. 2-1/2 in swallows big debris and is clumsy inside a car.
What not to pay for
- Shopping by peak HP
Two vacs with the same peak HP can clean very differently. Compare CFM, water lift and hose size instead.
- Drywall dust through the standard filter
Fine dust passes through and coats the room again. Fit a fine-dust filter and a bag first.
- The biggest tank you can find
A 16 gal vac is a chore to store and drag around a small home. Buy for the messes you really have.
Never vacuum gasoline, solvents or hot ashes, because the motor can ignite them. Plug into a GFCI outlet when you're picking up water. Leave dust that may hold asbestos or lead paint to a pro.
Questions
Do I have to take the filter out to vacuum water?
On most models, yes. Pull out the paper cartridge filter and any bag, and fit the foam sleeve if yours came with one. Your manual has the final word.
What size shop vac do I need for car detailing?
A 2.5 to 5 gal model with a 1-1/4 in hose. It reaches under seats, and you can carry it around the car. Bigger vacs work too, with a narrow hose adapter.
Can a shop vac replace my house vacuum?
For hard floors and the garage, it works. It's loud and bulky, and it has no spinning brush to lift dirt out of carpet. Keep both.
Written by the DIY Project team. We recommend by type and spec, cheapest option that does the job first. How we check
Updated October 3, 2026. Prices are estimates.