Pool Filling Time Calculator
Find out how long it takes to fill your pool, estimate the water cost, and get a projected finish time.
Heads up: This fill will take over 12 hours. Do not leave the hose completely unattended — check periodically to ensure the hose has not moved, the pool is not overflowing, and the water pressure is still flowing. Consider setting an alarm for the estimated finish time.
How Long Does It Take to Fill a Pool?
Fill time depends on pool volume and the total flow rate from your water source. The formula is: Hours = Pool Volume (gal) ÷ (GPM × Number of Hoses × 60).
- A standard garden hose delivers about 9 GPM at typical household pressure.
- A 5/8-inch hose delivers about 17 GPM — the most common residential hose size.
- A 3/4-inch hose can deliver 20–25 GPM.
- Some municipalities allow a temporary fire hydrant connection for faster fills — check with your water company.
A 20,000-gallon pool filled with a single 5/8" hose at 17 GPM takes approximately 20 hours. Two hoses cuts this to about 10 hours. Water cost varies widely by region — the national average is roughly $5–$8 per 1,000 gallons.
Check with your water utility before filling — many offer a one-time pool fill discount or sewer credit since pool fill water doesn't enter the sewer system.