How Long Does It Take to Fill a Pool With a Garden Hose?

Water falling from a spout into an indoor pool with blue tiles

Filling a pool with a garden hose takes anywhere from a few hours for a small above-ground pool to two or three days for a large inground one. The answer for your pool comes from two numbers: how many gallons it holds, and how many gallons a minute your hose delivers.

Hours to fill = gallons ÷ gallons per minute ÷ 60

A 15,000-gallon pool on a hose that delivers 8 gallons a minute takes 15,000 ÷ 8 ÷ 60, about 31 hours. Most people guess the flow and get the answer badly wrong, so the most useful thing you can do is measure it. It takes one minute.

Pool fill cost calculatorEnter your gallons and a bucket time to get the fill time and what the water will cost.

Step 1: know your gallons

If you don’t know your pool’s volume, work it out from its size. Length × width × average depth × 7.48 gives gallons for a rectangle; round pools use 3.14 × radius² instead of length × width. The pool volume calculator does every common shape, including ovals and kidneys.

Use the depth the water will actually reach, not the height of the wall. Most pools are filled to the middle of the skimmer opening, which is a few inches below the top.

Step 2: measure your hose’s flow with a bucket

Garden hose flow varies far more than people expect. Hose length, diameter, house water pressure and anything else running in the house all change it, which is why published figures for “a garden hose” disagree so widely. Your own number takes a minute to get:

Attach the hose you’ll use for filling, at its full length, with no spray nozzle.
Turn the outdoor tap fully open.
Time how many seconds a 5-gallon bucket takes to fill.
Divide 300 by the seconds. That’s your gallons per minute.

Bucket fills in	Your flow
75 seconds	4 gal/min
60 seconds	5 gal/min
38 seconds	8 gal/min
30 seconds	10 gal/min
25 seconds	12 gal/min

Do the test at the time of day you’ll be filling. Pressure is often lower in the morning and evening, when the neighborhood is showering and watering.

Fill times by pool size

These are calculated straight from the formula. Find your pool’s gallons and the flow closest to your bucket test.

Pool	Gallons (about)	At 5 gal/min	At 8 gal/min	At 12 gal/min
12 ft round, 3 ft water	2,500	8 hours	5 hours	3.5 hours
18 ft round, 4 ft water	7,600	25 hours	16 hours	11 hours
24 ft round, 4 ft water	13,500	45 hours	28 hours	19 hours
16 × 32 ft inground, 4.5 ft average	17,200	57 hours	36 hours	24 hours
20 × 40 ft inground, 5 ft average	29,900	100 hours	62 hours	42 hours

Hours to fill each pool from empty at three hose flows. A slow hose on a large inground pool runs about 100 hours, roughly four days. Your own bucket test tells you which bar is closest.

A large inground pool on a slow hose can take four days. That’s normal, not a sign that something is wrong. Only topping up a few inches? Multiply the inches by your pool’s gallons per inch from the pool surface area calculator, then divide by your hose flow.

How to fill a pool faster

Use a second outdoor tap. Two hoses on two separate spigots can nearly halve the time. A Y-splitter on one spigot usually adds little.
Shorten the hose. Use the shortest length that reaches. Every extra 25 or 50 feet costs flow.
Use a wider hose. A 3/4-inch hose loses less pressure than a 1/2-inch one over the same distance.
Take the nozzle off and make sure the hose isn’t kinked or coiled tightly.
Avoid peak times for household water use, and don’t run sprinklers or the washing machine while filling.
Order a water delivery if you need the pool full in hours rather than days. A truck can deliver several thousand gallons in one visit; the pool water delivery guide covers typical prices, and you can compare the cost against tap water in the fill cost calculator.

Filling an above-ground pool

Above-ground pools fill fastest because they hold less water, but the first few inches matter most. With an inch or two of water in, stop and smooth any wrinkles in the liner, working them toward the wall, before you carry on. Most liner instructions describe this step, and wrinkles are much harder to remove once the water is deep. Then fill steadily to the middle of the skimmer.

Filling from a well

A well can usually fill a pool, but running the pump for a day or more is hard on it and can run some wells dry. Fill in stages so the well can recover, and ask a well contractor if you’re unsure how much yours can supply. The guide to filling a pool with well water goes through testing and staged filling in more detail. Well water often carries iron, copper or manganese, which can tint the water green or brown once you add chlorine. Test for metals before balancing; the cloudy pool guide explains what metals look like in the water.

What it costs

Tap water is usually the cheapest option even for a big pool. At the EPA WaterSense national averages ($7.74 per 1,000 gallons for water, $16.83 with sewer), a 17,200-gallon pool costs about $133 in water, or about $290 if sewer is charged on it. Your own rates may be very different, so enter them in the fill cost calculator.

Once it’s full

New fill water is rarely ready to swim in. Start the pump, then test free chlorine, pH, alkalinity, calcium and stabilizer, and bring them into range in the right order with the opening planner. If the terms are new, pool chemistry for beginners explains what each number means. Once the pool is full, note the water level against the tile; if it drops faster than you expect, the pool water loss calculator turns the drop into gallons a day and runs a bucket test.

Common questions

How long does it take to fill a 10,000-gallon pool with a hose?

At 5 gallons a minute, about 33 hours. At 8 gallons a minute, about 21 hours. At 12, about 14 hours. Time a 5-gallon bucket to find your own flow; 60 seconds means 5 gallons a minute.

Will two hoses fill the pool twice as fast?

Only if each hose runs from a different outdoor tap. Splitting one spigot into two hoses usually adds little, because the tap and the pipe behind it limit the flow.

Does a wider hose fill faster?

Often, yes. A 3/4-inch hose loses less pressure over its length than a 1/2-inch hose, and a short hose beats a long one. Measure with the bucket test after any change to see the real difference.

Can I leave the hose running overnight?

You can, as long as you know roughly when the pool will reach the right level and someone can turn it off. Set a phone alarm or use a hose timer so the pool doesn't overflow and the water bill doesn't surprise you.

Sources

Data and Information Used by WaterSense, US Environmental Protection Agency (WaterSense)National average residential water and wastewater costs, used for the cost example.
NIST Special Publication 811: unit conversion factors, National Institute of Standards and Technology1 cubic foot = 7.4805 US gallons, used to turn pool dimensions into gallons.

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How Long Does It Take to Fill a Pool? Hose Times by Pool Size