My pool has the winter cover on. The water underneath, I am hoping, is clean. But the water on top of the cover is quite dirty.

What kind of pump should I use for discarding this water before opening the pool? I've seen some "wet/dry shop vac" type of pumps at local stores. Is any of these adequate? Will they fail if a few leaves enter along with the water?

It would be nice to have that pump double as garage sweeper (pour water, vacuum the water with the dirt from the garage floor), and so it would be nice if a shop-vac will fit the bill.

Another option is to use the winterizing pump, which I don't have. Though I may get it if I gather the courage to winterize myself. When winterizing the pool, a fairly strong pump is needed to clear water from the pipes, and I'm assuming that such a pump could also see double-use to vacuum the spring-time dirty water, but I'm not sure if using such a pump on the polluted water would make it contaminate the pool before winterizing.

  • I don't know how big you pool is, but there's more water there than you think. If it's nasty water a shop vac is probably best this time, and it will suck up leaves too. For next season get a pool cover pump and keep it pumped off all winter, less mess and the cover stays clean.
    – Tyson
    May 25, 2016 at 21:02
  • The (specialized) folks who closed the pool advised against removing the water. Their argument was that the dirt then bakes into the cover, whereas the water will make it possible to pump the dirt along. Both opinions may be valid. The trick is that the water on top of the cover remained pristine until early April, and then quickly started deteriorating, until (by end May) it's very green and almost entirely opaque.
    – Calaf
    May 25, 2016 at 21:34
  • Thanks for the hint that a pool cover pump exists. I see it now in stores. I'm guessing these are automated devices. Their yield is very low (judging by the price) but they are automated. As soon as they detect some water, they start pumping. Is that how they work, or do they need to be turned on/off manually?
    – Calaf
    May 25, 2016 at 21:36
  • Most have a float switch that I've seen.
    – Tyson
    May 25, 2016 at 21:37

2 Answers 2


Use a siphon. Get decent garden hose (that won't collapse if you draw a mild vacuum) and that's flexible enough to stay in the bottom of the pool area.

Run it from the center of the "puddle" to a point a couple feet below it in altitude, e.g. That storm drain.

From this bottom point, prime the siphon by sucking all the air out of the the garden hose. At this point, water will siphon continuously until the puddle is drained or the high end of the hose goes above water.

Once air gets into it, you'll hear a slurping sound, which means you lost the prime. Fix why that happened, and re-prime.

A shop-vac is an excellent way to suck on it. If you did it with your mouth, you'd be tempted to raise it up to your face, and that end must be below the intake end.

The greater the height differential, the faster the flow. The higher the peak is from the inlet, the more difficult it will be to prime.

  • Great idea, but I'm reluctant to prime the siphon with my lungs, and so I'm wondering. Could I just dump the garden hose in the pool, wait half an hour to be sure it's filled, then lock one side before pulling it out? If yes, what is the name of that "garden hose blocker"? Alternatively, do some shop vacs come with threading that is compatible with the standard garden hose threading?
    – Calaf
    Jun 1, 2016 at 21:07
  • Any cheapie hose valve would suffice, or your thumb. For vacuum use, I would just use my hand to block the empty space between the water hose and the vacuum hose, the seal doesn't have to be perfect, just in the ballpark. You could dunk the hose but would need to work essentially all the air out, too much will go to the top of the "hump" and break the prime. Or you could prefill it with fresh water from the tap. Jun 2, 2016 at 2:12

A wet/dry shop vac should be great for this, and it will be a useful tool for the rest of the year as well. The main limitation is going to be the amount of water you can "pump" before emptying the vac. You'll be limited to 5-10 gallons at a time depending on what you buy.

Leaves or any other dirt or trash will be fine. As long as it can fit through the nozzle and the hose, the vac will happily suck it up. I've used mine to suck water out of a hole when doing an irrigation repair and to clean up a major water spill in the house.

Follow all instructions for wet use. Normally the filter will need to be removed. Also, clean the vac immediately and let it dry when you are done. Old, dirty water gets moldy and nasty very quickly and can make the vac smell bad for the rest of its life.

  • Emptying a container of 5-10 gallons at a time will take ages. The only drain I can use (the rainwater drain on the street) is more than 50ft away, so carrying the container is not an option. Can I not hook up an extension pipe to the shop-vac and bypass its container altogether?
    – Calaf
    May 25, 2016 at 21:32
  • Some shop vacs have a drain hose connection where you could attach a hose, but you would have to suck up the vacs capacity of water, turn it off, open the drain, and allow it to drain (via gravity), then repeat. Because of the way the vac works, it can't suck and drain at the same time. It also can't "pump", it only sucks. It depends on how much water you have... I assumed it was a relatively small amount. Also, larger vacs are available. I think mine is 16 gallon.
    – JPhi1618
    May 25, 2016 at 22:40
  • @Calaf you don't understand how shop vacs work. They are NOT wet pumps. Water in the vacuum pump will instantly wreck the unit. They draw a vacuum on their bucket, which makes water suck into the bucket. Inside the filter cage is a ball which, if water starts rising toward the vacuum input, will be sucked into the vacuum inlet, plugging it. The motor will race (you know the sound) and you shut it down at that point and deal with the blockage, i.e. Drain the water. May 26, 2016 at 3:25
  • @Harper Thanks for taking the time to detect what I was indeed misunderstanding. What motivated my question in the first place is wondering how shop-vacs could be sold at such low price points. I'll take another pass at what is on the market and see if there I can get a wet pump that sees double use for sweeping the garage floor.
    – Calaf
    May 26, 2016 at 14:25
  • 1
    In general, water pumps like water and don't do well with air. It might exist, but I don't know of a water pump that would be happy pumping 100% water from the pool and an air-water mix from the garage floor.
    – JPhi1618
    May 26, 2016 at 14:29

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