Why Is My Pool Cloudy? Six Causes and the Test for Each

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Why is my pool cloudy? Usually one of six causes: free chlorine below 1.0 mg/L, pH above 7.6, total alkalinity above 200 mg/L, too little filtration (the whole volume should pass through the filter in 6–8 hours), high calcium, or dust from a new interior. A home test kit separates most of them.

The short answer

Home-pool chlorine: 1.0–3.0 mg/L, ideal 2. SA Health's guidance for pools at home. Below 1.0, the water is under-sanitised and cloudiness is often the first sign.
pH 7.2–7.6 for home pools (SA Health). NSW Health's public-pool advisory shows why: at pH 7.2, 63% of free chlorine is the strong disinfecting form; at 7.8, only 28%.
Total alkalinity above 200 mg/L is listed as a cause of cloudy water in NSW Health's public pool advisory document. SA Health's home range is 60–200 mg/L.
Filtration: the full volume through the filter in 6–8 hours, per SA Health and HealthyWA. For a 50,000 litre pool that is about 104 litres a minute for 8 hours.
A new concrete interior sheds fine dust for 3–4 weeks, according to a pool-service trade guide. It is the usual reason a brand-new or resurfaced pool is cloudy with normal chemistry.

Why a pool goes cloudy: the reading that separates each cause, home-pool targets and public-pool rules (read 30 September 2026)
Cause	The reading that points to it	Home-pool target (state health guidance)	Public-pool rule (NSW Health / Queensland Health)	First fix
Chlorine too low	Free chlorine below 1.0 mg/L on a DPD No. 1 test	1.0–3.0 mg/L, ideal 2 (SA Health). Stabilised outdoor pools: at least 2 mg/L below 26°C, 3 mg/L above (HealthyWA)	Outdoor pool min 1.0 mg/L; with cyanuric acid min 3.0 (NSW) or 2.0 (QLD)	Raise chlorine; if you have a salt chlorinator, test why it is not keeping up
pH too high	pH above 7.6	7.2–7.6 (SA Health); 7.2–7.8, 7.5 ideal (HealthyWA)	7.0–7.8 (NSW); 7.2–7.8 (QLD)	Lower pH with acid, added in small doses
Total alkalinity too high	Total alkalinity above 200 mg/L	60–200 mg/L, checked weekly (SA Health)	80–200 mg/L (NSW and QLD). NSW lists cloudy water and ‘pH lock’ above 200	Acid lowers alkalinity and pH together; re-test pH after
Not enough filtration	Chemistry in range but still cloudy; filter pressure gauge risen; pump hours short	Whole volume filtered in 6–8 hours (SA Health, HealthyWA)	Turbidity max 1 NTU, ideally under 0.5 (QLD); max 1.0 NTU (NSW)	Clean or backwash the filter; run the pump for a full turnover
Calcium too high	Calcium hardness above 400 mg/L, often with high pH and alkalinity	150–400 mg/L (SA Health)	Water balance index (LSI) between −0.5 and +0.5; positive means scale can form (QLD)	Replace some water with lower-calcium mains water
Dust from a new interior	Pool finished or resurfaced in the last few weeks; white dust settles on the floor; chemistry normal	No health-department figure	No health-department figure	Brush daily, clean the filter often; trade guidance says it sheds for 3–4 weeks

Why is my pool cloudy? Test in this order

Cloudy water is suspended particles the filter is not removing, or chemistry that is keeping them in the water. The order below is the order that costs least to check, and most of it uses the same home test kit.

Free chlorine. SA Health's guidance for pools at home puts free residual chlorine at 1.0 to 3.0 mg/L, with 2 mg/L ideal, and says to test pH and chlorine before use and at least once a day. Below 1.0, micro-organisms are growing faster than the chlorine can kill them, and haze is often the first visible sign.
pH. SA Health's home range is 7.2 to 7.6. High pH does not only cloud water; it weakens the chlorine you have. NSW Health's public pool advisory document tabulates it: at pH 7.2, 63% of free chlorine is hypochlorous acid, the strong disinfecting form; at 7.5, 49%; at 7.8, only 28%.
Total alkalinity. SA Health says to check it weekly ‘to prevent cloudy water, scale formation, metal corrosion’ and to keep it between 60 and 200 mg/L. NSW Health's table of alkalinity problems lists cloudy water, rough surfaces and clogged filters above 200 ppm.
Calcium hardness. SA Health's ideal is 150 to 400 mg/L. High calcium with high pH and alkalinity pushes the water towards scaling.
The filter and the pump hours, covered below, if every reading is in range.

The quotable version: if the chlorine, pH and alkalinity readings are all in range and the pool is still cloudy, the problem is almost always filtration, not chemistry.

If your pool has a salt chlorinator and the chlorine reading is the one that is low, the question moves to the chlorinator. Why a chlorinator stops making chlorine sets out the tests in order. If the haze has a green tint, go to why a pool turns green instead, because green has its own decision table.

Why is my pool cloudy white?

A milky white pool usually points to one of three causes, and each has its own tell.

Low chlorine in a salt pool after heavy use. HealthyWA says some domestic salt water chlorinators may not produce enough chlorine during heavy use, and that ‘a pool will turn a milky colour if overused and cannot be used safely until the water is clear.’ The tell is a low free chlorine reading after a party or a hot weekend.
Calcium coming out of solution. Queensland Health's public-pool guideline uses the Langelier Saturation Index to combine pH, alkalinity, calcium hardness and temperature, and says the index should sit between −0.5 and +0.5; above zero, scale can form. The tell is high calcium hardness together with high pH or alkalinity, and white scale on tiles or the chlorinator plates.
Dust from a new or resurfaced concrete interior. A pool-service trade guide describes it as fine calcium particles that shed for the first 3–4 weeks and says it is the most common reason a new pool looks cloudy in its first month. The tell is timing: the interior is new, and chemistry is normal. No health department publishes a figure for this, so treat the 3–4 weeks as trade guidance.

A pool that is cloudy white within weeks of being built or resurfaced, with normal chemistry, is usually shedding interior dust, and brushing plus filter cleaning is the fix, not more chemicals. What resurfacing involves and costs is on pool resurfacing costs in Australia.

Why is my pool water cloudy when the chlorine and pH are fine?

Then the filter is not removing particles fast enough, or the pump is not running long enough. SA Health and HealthyWA both say the filter system should be able to filter the pool's entire volume within six to eight hours, and should keep running while the pool is in use and for at least an hour afterwards.

The arithmetic, worked through. A 50,000 litre pool filtered in 8 hours needs 50,000 ÷ 480 minutes = about 104 litres a minute through the filter. If your pump delivers less than that through your filter and pipework, or runs for fewer hours, the pool does not get one full turnover a day. The method for your own pool is on how long a pool pump should run each day.

Three checks, all free:

Filter pressure. HealthyWA says rising pressure on the filter gauge means the filter is getting dirty and needs cleaning; sand and glass filters are backwashed, cartridges are removed and cleaned.
Baskets. A full skimmer basket or pump strainer cuts flow before the water reaches the filter.
Timer. One major chlorinator maker's manual lists ‘insufficient water flow’ and ‘insufficient water turnovers each day’ among its causes of cloudy water.

A filter that cannot turn the pool over in eight hours will leave it cloudy however well the chemistry is balanced. If the pump or filter turns out to be undersized or failing, the parts and what a quote should say about them are covered in pool equipment explained.

Home pool or public pool: which chlorine and pH numbers apply?

The most-quoted Australian pool numbers come from public-pool rules, and they are not written for backyard pools.

NSW Health's Public Swimming Pool and Spa Pool Advisory Document applies to pools the public uses, ‘but not including a pool situated on private residential premises.’ Its chemical criteria: free chlorine minimum 1.0 mg/L outdoors (3.0 with cyanuric acid), pH 7.0–7.8, total alkalinity 80–200 mg/L, cyanuric acid maximum 50 mg/L, and a further 1.0 mg/L of chlorine whenever pH is above 7.6.
Queensland Health's Water quality guidelines for public aquatic facilities (December 2019) sets free chlorine at minimum 1.0 mg/L without cyanuric acid and 2.0 mg/L with it, pH 7.2–7.8, alkalinity 80–200 mg/L and turbidity of at most 1 NTU. It says domestic owners may find it useful but should take water questions to a pool shop or pool contractor.
SA Health's Pools at home and maintaining them is written for domestic pools: chlorine 1.0–3.0 mg/L, pH 7.2–7.6, stabiliser 30–50 mg/L, alkalinity 60–200 mg/L, calcium 150–400 mg/L.
HealthyWA, also for home pools and spas, sets higher chlorine for stabilised outdoor pools: at least 2 mg/L when the water is below 26°C and 3 mg/L above it.

For a backyard pool in any state, the domestic guidance from SA Health and HealthyWA is the closest published target; the NSW and Queensland figures are legal or advisory minimums for public pools. The two sets agree on alkalinity's upper limit of 200 mg/L and differ at the edges on pH.

When a cloudy pool is an equipment or repair problem

Most cloudy pools clear with a chemical correction and a clean filter. The ones that do not usually point to equipment:

A chlorinator that cannot keep up, because the cell is scaled, worn or undersized for the pool.
A pump or filter too small for the pool's volume to achieve a turnover in 6–8 hours.
Water so far out of balance, for example very high calcium or alkalinity, that replacing part of it is quicker than chemical correction. Where the water can go depends on your water utility: see draining a pool to the sewer in NSW and the WA rules, and what the refill costs.

If a cloudy pool keeps coming back after the chemistry is corrected, look at what the equipment can deliver before buying more chemicals. When equipment needs replacing, ask for the same specification from several installers and compare pool quotes; pool businesses listed for Sydney, Brisbane, Melbourne and Perth are a starting point.

Common questions

Is it safe to swim in a cloudy pool?

Not until it clears. SA Health says a domestic pool should not be used if the disinfectant level or pH is outside the recommended range, or if the water is dirty or cloudy. Test chlorine and pH first, and swim again only once both are in range and the water is clear.

Can high alkalinity make a pool cloudy?

Yes. NSW Health's public pool advisory document lists cloudy water, pH lock, rough surfaces and clogged filters as problems of total alkalinity above 200 ppm. SA Health's home-pool range is 60 to 200 mg/L, checked weekly. Acid lowers alkalinity, and pH with it.

Why is my salt water pool cloudy?

Most often because the chlorinator is not producing enough chlorine for the load. HealthyWA says some domestic salt chlorinators cannot keep up during heavy use and the pool turns milky. Test free chlorine: below 1.0 mg/L, check the chlorinator's salt, the water temperature and the cell plates for scale.

What chlorine level should a home pool have in Australia?

SA Health says 1.0 to 3.0 mg/L of free residual chlorine, with 2 mg/L ideal. HealthyWA sets at least 2 mg/L for stabilised outdoor pools below 26°C and 3 mg/L above 26°C. Public pools have separate minimums set by each state's health department.

Why is my new pool cloudy?

A new concrete or pebble interior sheds fine dust as it cures. A pool-service trade guide says it lasts about 3 to 4 weeks and recommends hard brushing and frequent filter cleaning in that period. No health department publishes a figure for it, so ask your builder for their start-up instructions.

Sources

General information only, current at 2026-09-30. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.