A sump pump can drain a pool, but it's not the best tool for the job
A sump pump will move water out of your pool, but it works slowly and can damage the pump if you run it continuously. Sump pumps are built to handle groundwater seeping into a basement—small volumes over long periods. A pool holds thousands of gallons and demands faster drainage. If you have no other option, a sump pump can work for a small above-ground pool or to finish draining after you've used a better method first. For in-ground pools or large volumes, rent a submersible pump or call a pool service instead.
The real risk is heat. Sump pumps have a duty cycle—they are designed to run for short periods, then rest while water collects again. When you force one to run continuously for hours, the motor overheats and the thermal overload switch shuts it off to protect itself. This leaves you with a half-drained pool and a pump that won't restart until it cools. Repeated overheating shortens the pump's life by years.
Key Takeaways
- Sump pumps drain slowly (typically 2,000 to 3,000 gallons per hour) and are not designed for continuous high-volume use like pool drainage.
- Running a sump pump for hours on end can overheat the motor and shorten its lifespan significantly.
- You will need a discharge hose, a way to submerge the pump intake, and a safe place to send the water away from your foundation.
- Submersible pumps rated for pool drainage move water three to five times faster and cost $50 to $150 per day to rent.
- Check local codes before draining—some areas restrict where pool water can go or require a permit.
Why sump pumps are slow for pool drainage
A typical sump pump moves between 2,000 and 3,000 gallons per hour. An average above-ground pool holds 10,000 to 15,000 gallons. That means a sump pump alone would take 4 to 8 hours to empty it completely. An in-ground pool of 20,000 gallons would take 7 to 10 hours or more.
Speed is only part of the problem. The bigger issue is that sump pumps are not built for this kind of work. They have a limited thermal capacity—the motor can only handle so much continuous running before it gets too hot. Once the internal temperature reaches a certain point, a safety switch cuts power automatically. You'll hear the pump stop, and it won't restart until the motor cools down, which can take 30 minutes or longer. If you try to restart it too soon, the switch trips again. This cycle of overheating and shutting down is hard on the motor and can reduce the pump's total lifespan by several years.
What you need to set up a sump pump for pool drainage
Start with a discharge hose that fits your pump's outlet. Most sump pumps have a 1.5-inch or 2-inch outlet. Buy or rent a hose long enough to reach where you want the water to go—at least 25 feet away from your foundation, and ideally to a storm drain, dry well, or low spot in your yard where water won't pool against your house. The hose should slope slightly downward so water flows out rather than pooling inside it.
Submerge the pump intake in the deepest part of the pool. You can set the pump on the pool floor, or place it on a cinder block or platform so it sits a few inches above the bottom. This keeps sediment and debris from clogging the intake. find the discharge hose so it won't slip out during pumping, and make sure the intake strainer basket (if your pump has one) is clean before you start.
Plug the pump into a GFCI outlet (ground-fault circuit interrupter)—the kind with a test button, usually found in bathrooms or kitchens. Never use an extension cord; run a dedicated outlet to the pool area if you don't have one nearby. A GFCI cuts power when ready if the pump or cord touches water, preventing electrocution. If no outlet is within reach, have a licensed electrician install one rather than improvising with cords.
How to monitor the pump while it runs
Check the pump every 30 to 45 minutes. Feel the motor housing—it should be warm, not hot. If it's too hot to touch comfortably, shut it off and let it cool for at least 30 minutes before restarting. Listen for changes in sound; a grinding or rattling noise means debris has entered the pump and you should stop and clear the intake when ready. A high-pitched whine can also signal that the pump is running dry or the intake is partially blocked.
Watch the water level in the pool as it drops. You may need to reposition the pump so the intake stays submerged. Once the water gets shallow—usually when it's less than 6 inches deep—the pump will start sucking air, which can damage the impeller and create a loud cavitation sound. Stop when the pool is nearly empty rather than trying to drain the last few inches. If you need to remove that final water, use a wet-dry vacuum or a submersible pump designed for shallow water.
When to rent a submersible pump instead
For any pool larger than 5,000 gallons, or if you want the job done in under 4 hours, rent a submersible pump rated for pool drainage. These move 5,000 to 10,000 gallons per hour and are built to run continuously without overheating. Rental costs range from $50 to $150 per day depending on size and your location. Home Depot, Sunbelt Rentals, and local equipment rental shops all stock them.
A submersible pool pump comes with a discharge hose and usually a strainer basket to catch debris. Setup is the same as a sump pump—submerge it, attach the hose, use a GFCI outlet—but you can walk away for longer stretches because overheating is not a concern. The pump will drain a 15,000-gallon pool in 2 to 3 hours. If you're draining an in-ground pool, a rental pump is almost always the better choice because it saves you time and eliminates the risk of damaging your sump pump.
Check local codes before you drain
Some municipalities restrict where pool water can go. In areas with combined sewer systems, pool water may have to go to a storm drain rather than the street. In drought-prone regions, you may need a permit or be required to use the water for irrigation instead of letting it run off. Call your city or county public works department before you start—a five-minute call can save you from a fine or a cease-and-desist order.
If your pool has been treated with chlorine, let the chlorine level drop to near zero before draining, or the water may damage plants and harm aquatic life downstream. Test strips cost a few dollars at any pool supply store. Alternatively, some municipalities have hazardous waste collection days where you can dispose of chemically treated water. Never drain chlorinated water into a storm drain or onto a neighbor's property.
Frequently Asked Questions
Can I use my basement sump pump if it's currently in my basement?
Yes, but only if you're comfortable removing it temporarily. Turn off power at the breaker, disconnect the discharge line, and lift it out. Drain any water from the pit, then transport it to the pool. When you're done, clean the pump intake and strainer basket before reinstalling it in the basement. The whole process takes 20 to 30 minutes.
What happens if the pump runs out of water to move?
If the intake loses contact with water, the pump will suck air. This can damage the impeller and create a grinding sound. Stop the pump when ready and reposition it so the intake is submerged again, or shut it off if the pool is nearly empty.
Can I drain pool water into my neighbor's yard?
No. Direct the discharge hose to your own property, away from your foundation, or to a storm drain if local code allows it. Sending water onto a neighbor's land can create liability and may violate local ordinances.
How long can I safely run a sump pump continuously?
Most sump pumps are safe for 2 to 4 hours of continuous operation before the motor begins to overheat. Check the manufacturer's manual for your specific model. If you need to drain longer than that, rent a submersible pump instead or plan to drain in stages with cooling breaks between runs.
Do I need to turn off my pool filter while draining?
Yes. Turn off the filter pump before you start draining. If water level drops below the skimmer intake while the filter is running, it will suck air and damage the filter pump motor.