Why Is My Pool Water Brown? Iron, Manganese or Leaves

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Why is my pool water brown? Usually dissolved iron or manganese, often from bore water, that turned visible when chlorine was added or pH rose. Australia’s drinking water guideline treats iron above 0.3 mg/L as enough to precipitate. If no metal is present, the brown is tannin from leaves. A metals test at a pool shop separates the two.

The short answer

Brown straight after adding chlorine or raising pH points to iron. One pool-chemical maker says bore water often turns brown when pH is raised and that it can turn brown immediately after chlorine is added.
Iron precipitates at about 0.3 mg/L, the NHMRC’s Australian Drinking Water Guidelines say, and gives water a rust-brown look. Oxygen-depleted groundwater has been recorded at up to 100 mg/L.
Manganese stains darker, brown-black to purple. The guidelines set 0.05 mg/L as the aesthetic limit for drinking water.
Worked figure: 50,000 litres of bore water at 1 mg/L of iron carries 50 g of iron; at the 0.3 mg/L guideline it is 15 g. That iron stays in the pool until it is removed.
Greenish-brown with no metals is organic, usually leaves or plant matter, per one maker’s stain guide; a shock and a brush is the fix.

Brown pool water: what the colour and timing point to, the test and the fix (read 2 October 2026)
What you see	Likely cause	The test	Fix	Source
Water turns brown or rust-coloured right after chlorine, shock or a pH rise	Dissolved iron oxidised out of solution	Pool-shop metals test; was the pool filled or topped up from a bore?	Do not run it through the filter; metal remover, then floc and vacuum to waste	Pool-chemical maker’s bore-water guide (vendor); NHMRC iron guideline 0.3 mg/L
Brown-black or purplish water or stains	Manganese	Metals test for manganese	As for iron; a metal-specific stain remover for stains	Maker’s stain guide (vendor); NHMRC manganese aesthetic limit 0.05 mg/L
Greenish-brown water or stains under leaves, metals test negative	Tannins and organic debris	Leaves or seed pods in the pool or skimmer; stains match where debris lay	Shock, brush, run the pump overnight, brush again	Maker’s stain guide (vendor)
Muddy brown, particles settle when the pump is off	Soil or silt from runoff, river or dam water	A jar of pool water clears as it stands	Floc and vacuum to waste; then rebalance	Pool-chemical maker’s river and dam water guidance (vendor)
Green-tinted but clear after shocking	Copper, not iron	Metals test for copper	See the green-pool decision table	Live page: why a pool turns green

Why is my pool water brown after adding chlorine or shock?

Because the chlorine oxidised dissolved iron. Iron dissolved in water is close to invisible; once it is oxidised it comes out of solution as rust-coloured particles. Australia’s drinking water guidelines (NHMRC) set the iron limit at 0.3 mg/L on taste and on ‘precipitation of iron from solution’, and say high iron ‘give[s] water an undesirable rust-brown appearance’.

One major pool-chemical maker’s guidance on bore water describes it: raising pH ‘tends to precipitate the dissolved metals such as Iron so often the water turns brown and the walls are stained’, and ‘very often after adding chlorine to the pool the water will immediately turn brown’.

The timing rule: a pool that goes brown within minutes or hours of chlorine, shock or a pH increase has metal in it, and more chlorine will make it browner, not clearer.

If the tint is green rather than brown, the metal is more likely copper; why a pool turns green covers that case.

Why is my pool brown after filling it with bore water?

Bore water is the commonest source of iron and manganese. HealthyWA says it is preferable to fill a pool with scheme drinking water, that bore water means using more chemicals ‘especially if the water contains a lot of iron’, and that it ‘may also cause staining, due to the dissolved salts and metals’. SA Health says only treated mains water should be used to fill a pool and to ask the local council’s environmental health officer before using another source.

How much iron a fill brings in, worked through. Iron in mg/L times litres gives the iron load. A 50,000 litre pool filled with water at the 0.3 mg/L guideline carries 50,000 × 0.3 = 15,000 mg, or 15 g of iron. At 1 mg/L it is 50 g; at 5 mg/L, 250 g. The NHMRC records oxygen-depleted groundwater at up to 100 mg/L. Ask for the iron and manganese figures from your bore test before you fill, and do the multiplication.

The same pool-chemical maker says salt chlorinators should not be fitted to bore-water pools because the cell clogs quickly, and that if at all possible ‘it is better and cheaper to buy in fresh water’. Compare with what it costs to fill a pool with mains or carted water.

Every litre of bore water adds its iron to the pool, so the bore test result, multiplied by the pool’s volume, tells you how big the brown-water problem will be before you fill.

How do I fix brown pool water?

For metal, the published method from one pool-chemical maker for bore-water pools is: a metal stain remover, then a flocculant to drop the metal to the floor, then vacuum it to waste, not through the filter. Its warning: ‘Do not attempt to filter a brown pool as the metals will clog the filter.’ Only once the pH is right does it superchlorinate. Another maker’s stain guide says to have the water tested for metals at a pool shop first, because the stain remover should target the metal you have.

Get a metals test (iron, manganese, copper).
Hold off on more chlorine.
Treat with a metal remover or sequestrant as the label directs.
Floc and vacuum to waste; top up afterwards.
Rebalance pH and alkalinity to SA Health’s home ranges: pH 7.2–7.6, alkalinity 60–200 mg/L.

Vacuuming to waste sends water out of the pool, and where it may go depends on your water utility: see draining a pool to the sewer in NSW and the WA rules. If treatment has to be repeated after every top-up, replacing the water from a cleaner source can be the cheaper fix; the cost to empty and refill a pool sets out what that involves.

Brown pool water caused by metal is fixed by removing the metal, not by filtering or chlorinating it.

Why is my pool water brown or tea-coloured with no metals?

Then it is organic. One major maker’s stain guide reads colour this way: greenish-brown is ‘most likely organic stains caused by leaves or other plant matter’; greenish-brownish-red indicates iron; brownish-blackish-purple is manganese. Its fix for organic staining is to balance the water, shock the pool (it recommends at night), brush, run the pump overnight and brush again.

Muddy brown water after a storm or a top-up from a river or dam is suspended soil rather than a dissolved colour. The same bore-water guidance treats river and dam water as high in organics and usually cloudy, settled with a flocculant and vacuumed to waste. Overhanging trees that keep refilling the skimmer are a design question; covers that keep leaves out are priced in pool cover costs and payback.

If the metals test is negative, brown pool water is leaves, tannins or soil, and chlorine and brushing clear it. If the cause turns out to be the equipment or the interior, ask several businesses to quote the same work and compare pool quotes; listed businesses in Perth, Toowoomba and Adelaide are a starting point.

Common questions

Is it safe to swim in a brown pool?

Wait until it is clear and in range. SA Health says a home pool should not be used if chlorine or pH is outside the recommended range or the water is dirty or cloudy.

Why did my pool turn brown after shocking?

The chlorine oxidised dissolved iron or manganese. The Australian Drinking Water Guidelines say iron precipitates around 0.3 mg/L and turns water rust-brown. Get a metals test before adding more chlorine.

Can I fill my pool with bore water?

HealthyWA says scheme water is preferable and that bore water raises chemical use, especially with iron, and can stain. SA Health says to ask your council’s environmental health officer before using a source other than mains water.

Should I run the filter on a brown pool?

Not to remove metal. One pool-chemical maker warns that filtering a brown pool clogs the filter with metal; it recommends a metal remover, floc and vacuuming to waste.

Sources

General information only, current at 2026-10-02. 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.