How Long Does It Take to Fill a Pool?
Fill time is your pool volume divided by the flow rate. A single garden hose runs about 9 gallons a minute, so most pools take a day or two. Here is the chart and the math.
By the Calculate My Reno Team / Published
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Fill time is just how much water the pool holds divided by how fast it comes in:
hours = pool gallons ÷ flow rate (gallons per minute) ÷ 60
A single garden hose runs at roughly 9 US gallons (about 34 litres) a minute - around 540 gallons an hour. That is the number behind the “a day or two” rule of thumb for most backyard pools.
First, get your gallons
You need the pool volume to start. The pool volume calculator gives it in gallons or litres, or see how many gallons is my pool for the common sizes.
Fill time by volume
Hours of continuous filling, for a single hose at about 9 gallons a minute and a high-flow setup (two hoses or a 3/4 inch hose) at about 17 gallons a minute:
| Pool volume | One hose (~9 gpm) | High flow (~17 gpm) |
|---|---|---|
| 5,000 gal | ~9 hours | ~5 hours |
| 10,000 gal | ~18 hours | ~10 hours |
| 15,000 gal | ~28 hours | ~15 hours |
| 20,000 gal | ~37 hours | ~20 hours |
| 25,000 gal | ~46 hours | ~25 hours |
| 30,000 gal | ~56 hours | ~29 hours |
Because flow rate varies so much with pressure and hose size, treat these as a guide and time your own hose to be sure.
Find your own flow rate
Run the hose into a bucket of known size and time how long it takes to fill:
flow rate (gpm) = bucket gallons ÷ minutes to fill
A 5 gallon bucket that fills in 35 seconds is about 8.6 gallons a minute. Use that rate in the formula above for an accurate fill time.
Ways to fill faster
- Two hoses from separate taps roughly halve the time.
- A shorter, wider hose (3/4 inch) loses less pressure than a long thin one.
- A bulk water delivery by tanker can fill a large pool in under an hour - often worth pricing against metered tap water.
- Ask your water utility about a fill or sewer credit before you start, since the water does not go down the drain.
Worked example
A 16 by 32 ft pool holding about 19,000 gallons, filled with one hose at 9 gallons a minute:
minutes = 19,000 ÷ 9 = 2,111 minutes
hours = 2,111 ÷ 60 = about 35 hours
So a day and a half of continuous filling - or about half that with a second hose running.
Frequently asked questions
How long does it take to fill a pool with a garden hose?
A single garden hose delivers roughly 9 US gallons (about 34 litres) a minute, so it fills about 540 gallons an hour. A 15,000 gallon pool takes around 28 hours of continuous filling, and a 20,000 gallon pool about 37 hours. Flow varies with hose diameter, length and water pressure, so time the first few minutes into a known container to get your own rate.
How do I calculate pool fill time?
Divide the pool volume by the flow rate, keeping the units consistent. In US units: gallons divided by gallons-per-minute gives minutes, so divide by 60 for hours. A 12,000 gallon pool at 9 gallons a minute is 12,000 ÷ 9 = 1,333 minutes, about 22 hours. In metric, divide litres by litres-per-minute.
How can I fill a pool faster?
Run two hoses from separate taps to roughly halve the time, use a larger 5/8 or 3/4 inch hose kept short, and connect to an outdoor tap close to the supply for the best pressure. For a large pool it is often quicker and sometimes cheaper to order a bulk water delivery by tanker, which can drop several thousand gallons in under an hour.
Will filling my pool spike my water bill?
Yes - filling is a one-off but real cost, since a typical pool is 10,000 to 25,000 gallons of metered water. Some water utilities offer a fill or sewer credit if you tell them you are filling a pool, because the water does not return to the sewer. Ask before you fill, and check whether a tanker delivery works out cheaper than metered tap water in your area.