Sign up ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

Can a wet vac effectively be used as a pump to move water?

I figure if a basement floods, that this can serve as double duty.

share|improve this question

7 Answers 7

up vote 1 down vote accepted

City employee, talked the boss into buying us a shop vac about 5 years ago ,so i saw the one with a built in "water pump",at Lowes and gave it try. Why not? Not my money if it turns out to be junk, lol. I used it to clean out one of our sump pump pits at the bottom of one of our dry wells at a sewer pump station . everything is around 40 feet straight down in the ground. We all had serious doubts about this"pump" but if it worked it would have saved several hours of work, not having to send the tank up on the hoist after filling it up to be emptied. Hooked a water hose to the pump discharge, put on the pump extension /filter in the tank,ran the water hose straight up 40 feet and about another 10 feet to the toilet. Can you believe it WORKED? ! And worked perfectly. Only once or twice i had to stop so the pump could catch up from what i was sucking up, but 2.5 inch suction hose VS. 5/8 inch discharge, plus the height, man you can not ask for better. It was a full stream and lots of pressure on the discharge side,probably could have pumped 80 feet straight up. 5 out of 5 stars. Buy it. I protect that shop vac like its my own,dont want any monkeys screwing it up.

share|improve this answer

I'm draining my pool cover right now with the shop vac. Run it until the water hits the top. When you pull the lid motor you've already created the suction you need. It is slow but steady. No need to drill a hole in the side. It just pours out the top.

share|improve this answer

Just use the hose from the shop vac. Drained my 560 gal spa in less than 15 min. Submerge hose in water to prime and pull out end with extensions to drain. works like a charm.

share|improve this answer
Were you actually using the shop vac, because it sounds like you were just siphoning out the water. – Niall C. Feb 14 '13 at 17:12
...and if you're trying to siphon a basement, it won't work because you'll have negative hydraulic head. – alx9r Feb 15 '13 at 2:05
As noted elsewhere, some shop vacs apparently can pump to some degree. – keshlam Oct 26 at 12:40

Drill a hole near the bottom of the vac canister and plug it; when the canister is half full remove the plug and water will drain out of the canister but still keep a vacuum as long as water doesn't empty. Size the hole properly: not so small that the canister fills, or so large that it empties too quickly.

share|improve this answer
How do you determine the size of the hole, or would you just use trial and error? – Tester101 Dec 31 '12 at 18:23

About 15 years ago, when I was helping my parents open up their above-ground pool for the summer, we used a small shop-vac to pump the water from the pool cover and dump it onto the lawn. Basically we just took the canister off the vacuum, turned it on, and stuck the hose in the water. The water was moved horizontally, not vertically, so I'm not sure about draining a basement, but the vacuum did operate continuously for some time and didn't seem to be adversely affected.

share|improve this answer
Not sure they still make any shop vac's like that (didn't realize they ever did). All the ones I've seen connect the hose to the canister. Many also include a float inside the filter space to shutoff the airflow before moisture gets into the motor. – BMitch Aug 31 '11 at 11:37

Some Shop Vacs have a "water pump" feature. You can attach a garden hose to a side port on the vac, and rather than just dumping the water in the canister, it will actually pump the water to another location.

If you do not have such a vac, you can suck water until the canister fills up. Then you have to dump the water somewhere. (Note: A shop vac full of water is really heavy.)

share|improve this answer
This is very interesting! Thanks! I assume that gregmac's comments on the above answer are "modifiers" of this. – mbrownnyc Aug 30 '11 at 13:09
I haven't ever used a shopvac that actually had this "water pump" feature, so I can't comment. – gregmac Aug 30 '11 at 22:35
Great feature. Though if I'm ever vacuuming up so much water to need this, I think I'd want a sump pump. – BMitch Aug 31 '11 at 11:38
Shop Vac water pump feature is advertised for draining a hot tub. I haven't used it for anything that big, just a few gallons. – msemack Aug 31 '11 at 12:43

A pump can operate continuously to move water between two locations. The wet vac will suck water into the cannister, but you'll need to continuously stop, and dump that water, before it reaches the top of the vacuum. If you're looking at a flooding risk, I'd want the pump.

share|improve this answer
Thanks, I'm curious about the evacuation of water. What if you just place the body outside of the canister which it usually calls home? I wouldn't expect this to be a continuous proposition, but only in case of emergency. – mbrownnyc Aug 29 '11 at 13:05
@mbrownnyc, Water isn't sucked through the vacuum motor, it's sucked into the canister body via an air vacuum created by the motor on top. The hose it attached to the canister, not the vacuum. I also don't think you'll see a lot of suction power from smaller shop vacs, enough to pull up a spill, but not enough to suck a bucket of water up 5 feet vertically. – BMitch Aug 29 '11 at 13:18
Okay... thanks! – mbrownnyc Aug 29 '11 at 13:36
In my experience, most shop vacs -- even the most expensive "contractor-grade" ones -- will not be able to maintain the pipe full of water: you have to suck a mix of air+water or else it will just stall. A trash pump will work the best with large amounts of water (can be rented at any rental place), and a regular sump pump will be the cheapest and most effective option. – gregmac Aug 29 '11 at 22:57

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.