How long can you leave water in a paddling pool?

Part of our pool and hot tub water guide

The pool went up on Saturday, it rained on Sunday and it is now Wednesday. How long can that water stay in? You can see what your own pool water is doing with a 20-in-1 test strip, and the UK sources say more below.

By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026

How long can you leave water in a paddling pool?

The sources we read give no number of days and advise emptying the pool after use. The nidirect garden safety page says to make sure paddling pools are emptied after every use. RoSPA says to empty them straight after use and put them away, because rain can refill them. The Pool Water Treatment Advisory Group (PWTAG) code of practice is written for public pools and lists paddling pools and domestic pools as not covered.

Why do the sources say to empty it rather than keep it?

Because each body is worried about something different, and none sets a water change schedule.

• Drowning. nidirect says drowning is silent, so you will not necessarily hear any noise or struggle. RoSPA says young children can drown in very small amounts of water.
• Mosquitoes. UKHSA gave its standing water advice as a precaution after invasive Aedes aegypti mosquitoes were found at homes in east London. It assessed the risk to the public as very low and said the species is not established in the UK.
• Germs. UKHSA's Cryptosporidium advice says people can get it by swallowing contaminated recreational water, including swimming pools, and advises avoiding swallowing water in lakes and swimming pools. It does not mention paddling pools. PWTAG, writing about public pools, calls Cryptosporidium chlorine-resistant. If you are concerned about your health or your child's, UKHSA says to contact your GP.

Why might your own pool water differ from a rule of thumb?

A rule of thumb, or a figure from someone else's garden, does not tell you what is in your own pool, and the sources give several reasons it can differ.

• The fill water. PWTAG says mains water, especially from rivers or reservoirs, is likely to contain some or all of organic materials, lime and other alkalis, and phosphates added to stop lead and copper dissolving from pipework. It says those phosphates encourage algal growth in a pool. That is its description for pools generally, and what reaches your hose depends on where your tap water comes from.
• Who uses it. PWTAG says the chief source of pool pollution is the bathers, naming sweat, skin particles, mucus, urine and faeces. It adds that suspended material can shelter microorganisms from disinfectant. On our reading, two pools of the same size can differ with who uses them and for how long.
• The weather. RoSPA says rainfall can refill paddling pools, so what is in yours may not be what you put in.

“A figure from someone else's garden or a rule of thumb won't tell you what's in your own pool, because your fill water, who uses it and the weather all change it. If you want to know what your water is doing, dipping a strip in the tap water and again in the pool is a sensible way to compare the two.”

What one reader found

In a Mumsnet thread dated 13 July 2022 asking how many days people keep their paddling pool water, one poster said 2 days. Theirs was a small, toddler-sized pool, and they said "Any longer and the grass underneath starts dying off." They emptied the water onto their plants and refilled the next day in a different spot if the weather was still warm. That is one household's habit, not an official figure. Our grey water guide covers reusing water on plants. Shared on Mumsnet.

Is it different for a bigger pool or a hot tub?

We found no interval for a bigger home pool either. PWTAG's code lists domestic pools as not covered, and its public pool figures, such as replacing water at 30 litres per bather, are not a schedule for a home pool. For hot tubs, nidirect says to make sure they are covered when not in use and that children under five should not go into a hot tub due to temperatures, chemicals and drowning risks. See our hot tub water change guide.

What can a test strip show on paddling pool water?

A 20-in-1 test strip indicates pH, chlorine and alkalinity bands at the moment you dip it, so repeat dips show whether they shift while the water stands. Fill a clean glass or cup from the pool, dip one strip, wait 30 to 60 seconds and match the pads to the chart. You can also enter the colours in the free results checker, or scan the QR code on the chart (see how to test your water at home). We have not run strips on paddling pools, so the points below are our own reading of the chart steps.

• If you add chlorine, the free chlorine pad has steps at 0, 0.5, 1, 3, 5, 10 and 20 mg/L. The sources we read give no range for a home paddling pool to compare it with.
• A dip at the start and end of a day shows whether the pH, chlorine or alkalinity bands moved. That is a change in colour steps, not a verdict on the water.
• No pad responds to germs, algae, phosphates or mosquito larvae. The optional rapid bacteria test is a presence screen for coliforms in a small sample, not a count, and we do not claim the test for pool water.

Any figure you read elsewhere is an average, and your pool may differ because, as PWTAG says, mains water is likely to contain varying organic materials, alkalis and phosphates, and bathers add their own pollution. The pH, free chlorine and alkalinity pads are the ones that matter here, and a change in colour step between the start and end of a day indicates the water shifted while it stood. Best pack: 20 strips, enough for start-and-end-of-day dips on 10 days (our arithmetic), £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit

Your paddling pool water questions

How long can you keep water in a paddling pool? How long can you keep paddling pool water? How long can you leave paddling pool water? How long can paddling pool water last?

In the sources we read, no time limit. nidirect and RoSPA say to empty the pool after use, and UKHSA says removing standing water, including in paddling pools, can help reduce mosquito breeding.

How often should you change paddling pool water? How often to change paddling pool water?

We found no interval in those sources. PWTAG's 30 litres per bather is a public pool figure.

How long is paddling pool water safe?

We found no time limit in those sources. UKHSA advises avoiding swallowing water in swimming pools, without naming paddling pools.

How long can water stay in an inflatable pool? How long can you leave water in inflatable pool?

The sources we read do not separate inflatable pools from other paddling pools.

Sources

1. Royal Society for the Prevention of Accidents, Garden safety (drowning, emptying paddling pools, rain refilling them, garden chemicals; undated page; read 29 October 2026).
2. nidirect (Northern Ireland government), Garden safety (drowning, 5 centimetres, empty paddling pools after every use; undated page; read 29 October 2026).
3. UK Health Security Agency, Invasive mosquito species detected in east London (3 September 2026; standing water in paddling pools; species not established, public risk very low; read 29 October 2026).
4. UK Health Security Agency, Cryptosporidium: public advice (1 November 2023; swimming pools, avoid swallowing water, contact your GP; read 29 October 2026).
5. Pool Water Treatment Advisory Group, Code of Practice: The management and treatment of swimming pool water (July 2021, updated July 2025; section 1.8 pools not covered, section 3 mains water, bather pollution, Cryptosporidium, 30 litres per bather; read 29 October 2026).
6. Mumsnet, How long do you keep water in your paddling pool? (forum thread, post dated 13 July 2022; one household's experience, not official guidance; read 29 October 2026).
7. WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, optional rapid coliform test read after 24 to 48 hours, from £3.99 for 10 strips, free 2nd Class delivery on every order) and results portal. The strip-chart points are WaterKit's own reading of the colour chart steps.

Contains public sector information licensed under the Open Government Licence v3.0.