Domakihub Pool Water Turned Brown? Find the Cause and Fix It Fast
Dissolved metals in your water oxidise the moment chlorine hits them — here is how to clear it up before staining sets in.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
Nothing stops a swim faster than opening your pool to find water the colour of rust or weak tea. The video above shows exactly what happens when metals in the water react with chlorine, and this guide gives you the practical steps to reverse it — without draining the pool. Whether you manage a private villa, a holiday rental, or a hotel pool in Greece, this is a problem worth solving quickly: dissolved iron and copper stain plaster, grout, and vinyl within days if left untreated.
Why Greek Pool Water Is Especially Vulnerable to Metal Problems
Greece has a high proportion of properties drawing water from private wells, particularly on islands and in rural areas. Well water in Greece is often rich in dissolved iron — sometimes at levels far above what municipal supplies carry. Old copper pipework and brass fittings found in many older villas can also leach copper ions into the pool over time, especially when the pH drifts low and the water becomes corrosive.
The metals themselves cause no discolouration while the water sits untreated. The problem begins the moment you add chlorine or a chlorine-based shock product. Chlorine is an oxidiser, and it converts soluble (invisible) iron into insoluble iron oxide — rust — which is what turns the water brown or orange. Copper oxidises to a blue-green tint. Both are harmless to swim in at low concentrations, but both will stain pool surfaces rapidly.
How to Tell Metals Apart from Other Brown-Water Causes
Brown water can occasionally have other causes — algae in an early growth stage, silt from a heavy rainstorm, or a filter that has stopped running. The key diagnostic test is timing: if the water turned brown within minutes or hours of adding chlorine or shock, metals are almost certainly the culprit. Algae turns water green or murky, rarely rust-brown, and the change is gradual rather than sudden.
A simple confirmation is a metal test strip or a drop-based iron test kit, available at any pool supply shop. If iron reads above 0.3 mg/L or copper above 0.1 mg/L, you have a metals problem. Note the pH and alkalinity too — you will need both in the normal range before treatment is effective.
5 Steps to Clear Brown Pool Water Caused by Metals
- 1
Stop adding chlorine immediately
If you have just shocked the pool and the water has turned brown, do not add any more chlorine. Additional oxidiser will continue converting dissolved metals into visible particles and make the problem worse. Run the pump and filter to circulate the water, but hold off on any further chemical additions until you have completed a water test.
- 2
Test and balance pH and alkalinity
Sequestrant products — the chemicals that bind metals and hold them in solution so they can be filtered out — work best at a pH of 7.2 to 7.6 and total alkalinity of 80 to 120 ppm. If pH is outside this range, adjust it first using pH reducer (sodium bisulphate) or pH increaser (sodium carbonate). Skipping this step means the treatment works slowly or incompletely.
- 3
Add a metal sequestrant at the label dose
A sequestrant (also sold as a metal remover or chelating agent) does not actually remove metals from the water — it wraps around the metal ions and keeps them dissolved rather than letting them precipitate out as visible particles or stains. Add the product with the pump running, distributed around the pool's perimeter. Most products recommend a starting dose based on pool volume, with a repeat dose after 24 hours if staining is severe.
- 4
Run the filter continuously and backwash or clean it
Over the next 24 to 48 hours the filter will trap the metal-laden particles as they are processed out of the water. Backwash a sand filter, rinse a cartridge filter, or regenerate a DE filter more frequently than usual during this period — a clogged filter cannot do the job. The water should progressively clear from brown back to blue as the filter removes the oxidised particles.
- 5
Address the source to prevent recurrence
Once the water is clear, identify where the metals are entering the pool. If you are filling from a well, fit an inline pre-filter with a metal-reduction cartridge on the fill hose. Have the well water tested at a laboratory to know your baseline iron and manganese levels. If old copper fittings are the source, maintain pH above 7.2 consistently — acidic water accelerates copper leaching. A small weekly maintenance dose of sequestrant (half the treatment dose) helps keep residual metals bound during the swim season.
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FAQ
- Is it safe to swim in brown pool water caused by iron?
- At the iron concentrations that typically cause discolouration (0.3 to 2 mg/L), the water is not toxic, but swimming is not advisable. The oxidised particles are fine enough to irritate eyes and skin, and chlorine levels are often depleted after the oxidation reaction, meaning the water is no longer properly sanitised. Clear the problem before anyone swims.
- Can I use vitamin C (ascorbic acid) instead of a sequestrant?
- Ascorbic acid is a popular DIY trick and it does work as a temporary fix — it reduces iron oxide back to its soluble form, clearing the colour within minutes. However, it also consumes a significant amount of chlorine and does not remove the metals from the water. Without a follow-up sequestrant treatment and ongoing maintenance, the water will turn brown again the next time you add chlorine. Use ascorbic acid for a quick visual reset, then follow up with proper sequestrant treatment.
- How much does professional pool metal treatment cost in Greece?
- A pool technician visit to diagnose and treat a metals problem typically costs between €80 and €200 depending on pool size, the severity of the discolouration, and whether staining has begun to set into the surfaces. DIY sequestrant products cost €15 to €40 per treatment depending on pool volume. For pools on well water or with older copper plumbing, budgeting for a small weekly maintenance dose of sequestrant throughout the season is far cheaper than replastering stained surfaces.