How long does it take to fill a 20,000 gallon pool, and what does it cost?
At 7.5 gallons per minute from one hose, a 20,000 gallon pool takes about 44.4 hours (1.9 days). With example rates of $5 per 1,000 gallons for water and $6 for sewer, the fill costs about $220.00: $100.00 of water and $120.00 of sewer.
How to work it out
- One hose: 5 gal ÷ 40 s × 60 = 7.5 gpm
- 20,000 gal ÷ 7.5 gpm ÷ 60 = 44.4 hours (1.9 days)
- Water: 20 thousand gal × $5 = $100.00
- Sewer: 20 thousand gal × $6 = $120.00
Twenty thousand gallons is a mid-size inground pool, like a 16 × 32 with a diving end. That is close to two days on a single hose, and enough water that the sewer line on your bill can cost more than the water — which is why it is worth a phone call to the utility before you start.
Adjust for your project
More options: Truck
- In days (running non-stop)
- 1.9 days
- Your hose flow
- 7.5 gpm per hose (450 gal an hour)
- Water cost
- $100.00
- Sewer charge
- $120.00
- Water and sewer
- $220.00
- Ask your utility about a pool-fill sewer credit or adjustment before you fill; some offer one because the water never reaches the sewer.
- A hose flow meter on the fill tells you the exact gallons that went in — the best volume figure you will ever have for dosing chemicals.
20,000 gallons by number of hoses
| Hoses | Time to fill | In days (running non-stop) | Water and sewer |
|---|---|---|---|
| 1 hose | 44.4 hours | 1.9 days | $220.00 |
| 2 hoses | 22.2 hours | 0.9 days | $220.00 |
| 3 hoses | 14.8 hours | 0.6 days | $220.00 |
| 4 hoses | 11.1 hours | 0.5 days | $220.00 |
Cutting the time and the bill
- More taps. Two hoses on separate spigots bring the fill to about 22 hours, three to under 15. Hoses split off one tap don’t help much.
- Ask about sewer. In this example, sewer at $6 per 1,000 gallons adds $120 to $100 of water. Utilities that offer a pool-fill sewer credit or adjustment may want you to arrange it before you fill.
- Tiered rates. Some utilities raise the price above a monthly threshold. A 20,000-gallon fill can push the whole month into a higher tier; split the fill across a billing date if your utility allows it and the pool can wait.
- Trucked water. A hauler with 6,000-gallon loads would need 4 trips. At an example $300 a load that is $1,200 — much more than the tap, but done in hours, and nothing drawn from a well.
After the fill
Twenty thousand gallons of fresh water starts with no chlorine and usually no stabilizer. The worked page for how much chlorine for a 20,000 gallon pool uses the same volume, and the pump side is on what size pump for a 20,000 gallon pool. Half the size is on how long to fill a 10,000 gallon pool with a garden hose.
Different size? Use the full Pool Fill Time & Water Cost Calculator.
What you’ll need
- Hose water flow meterBudget price
Screws onto the hose and counts gallons, so you know exactly how much went in — and your real fill rate.
See options on Amazon (opens in a new tab) - Hose-end pre-filterBudget price
Takes out sediment and some metals when you fill or top up from well or hard city water.
See options on Amazon (opens in a new tab) - Liquid pool chlorine (sodium hypochlorite)Budget price
Adds chlorine without stabilizer or calcium. Strength is printed on the label — commonly 10% or 12.5% — and it weakens with age and heat, so buy it fresh.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How long to fill a 20,000 gallon pool with three hoses?
About 14.8 hours with each hose on its own tap at 7.5 gallons per minute.
How many water trucks to fill a 20,000 gallon pool?
With example 6,000 gallon loads, 4 truckloads, about $1,200.00 at an example $300 a load.
Other common sizes
Sources
- NIST Handbook 44, Appendix C — General tables of units of measurement (opens in a new tab) — 1 US gallon = 231 cubic inches = 3.785 litres.
- US EPA WaterSense — Pool water efficiency (opens in a new tab) — Using a pool cover can prevent up to 95 percent of pool water evaporation — water you would otherwise refill.
- Intex — Ultra XTR 24 ft × 52 in round pool (opens in a new tab) — Water capacity 12,481 gallons.