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Quick Answer
The time it takes to drain an above-ground pool depends on the size of the pool, the flow rate of the drain, and whether you use any accessories like a submersible pump. For a typical 15-20 foot round above-ground pool containing 12,000-18,000 gallons of water, it will take 6-12 hours to drain it completely using just the drain in the bottom. With a submersible pump, you can drain it in 2-3 hours.
Drain Flow Rates
Most above-ground pools have a drain hole in the bottom center that is 1.5-2 inches wide. This allows gravity to slowly pull the water out of the pool and into a garden hose that you attach. The flow rate through these drains is typically:
| Drain Diameter | Flow Rate |
|---|---|
| 1.5 inches | 5-8 gpm |
| 2 inches | 8-12 gpm |
gpm = gallons per minute
As you can see, the drain allows water to be pulled from the pool at 5-12 gallons per minute. This slow flow rate is why it can take 6 hours or longer to drain an average above-ground pool using just the drain.
Pool Size and Volume
The size of your above-ground pool greatly impacts the total drain time. Larger pools hold more gallons of water that must be removed. Some typical above-ground pool sizes and capacities are:
| Pool Size | Gallons |
|---|---|
| 12 ft Round Pool | 6,000-9,000 gal |
| 15 ft Round Pool | 12,000-15,000 gal |
| 18 ft Round Pool | 15,000-18,000 gal |
| 24 ft Round Pool | 20,000-24,000 gal |
As you can see, the larger the pool, the more water it holds that must be drained out. This directly correlates to a longer total drain time.
Drain Time Calculation
To estimate the total time to drain an above-ground pool through its bottom drain:
1. Determine the total gallons of water in the pool. Refer to the pool size chart above or multiply L x W x Avg Depth x 7.5 gallons (for the volume of 1 cubic foot of water).
2. Determine the flow rate of your drain size. Refer to the drain flow rate chart above.
3. Divide the total gallons by the drain flow rate in gallons per minute (gpm) to get the total minutes required.
4. Divide the total minutes by 60 to convert to hours.
For example, for a 15 ft round pool containing 15,000 gallons, with a 2 inch drain flowing at 10 gpm:
Total Gallons: 15,000 gal
Drain Flow Rate: 10 gpm
15,000 gal / 10 gpm = 1,500 minutes
1,500 min / 60 min/hr = 25 hours
Therefore, it would take approximately 25 hours to drain this 15 ft round above-ground pool using just the bottom drain.
Using a Submersible Pump
You can speed up the drain time significantly by using a submersible pump. These pumps attach to a garden hose and can pump water out at 30-50+ gallons per minute.
At a pump rate of 30 gpm, the example 15 ft pool above would drain in:
15,000 gal / 30 gpm = 500 minutes
500 minutes / 60 = 8 hours
So the drain time decreases from 25 hours to just 8 hours with a good submersible pump!
Submersible pumps are available on Amazon and home improvement stores for $100-200.
Additional Draining Tips
Here are some additional tips for quickly and safely draining an above-ground pool:
– Use a thicker 1.5 inch diameter garden hose instead of a standard 0.75 inch hose to reduce friction and allow faster water flow.
– Make sure the drain hose slopes downhill so gravity helps increase the flow rate. Avoid uphill sections.
– Monitor the draining frequently in case of clogs at the drain screen or in the hose.
– Plug in the submersible pump (if using one) to an outdoor GFCI outlet for safety.
– Start draining in the early morning to allow ample daylight. Draining can take 6+ hours with just the drain.
– Drain onto grass or landscaping that needs watering. Avoid draining onto the concrete pad around the pool.
Conclusion
Draining an above-ground pool through the bottom drain hole takes 6-12 hours typically, depending on the pool size. Smaller pools under 15 ft across may drain in 5-8 hours, while larger pools above 18 ft can take up to 12-15 hours with just the drain. Using a submersible pump can reduce the drain time to just 2-4 hours. Safety is paramount when draining a pool, so monitor the process and use a GFCI outlet if using a pump. With patience and the right process, an above-ground pool can be drained in a reasonable time.