If your borehole water leaves orange-brown stains or a metallic taste, you’re dealing with dissolved iron (Fe²⁺)—common in Western Cape aquifers. The most reliable, SANS-241-aligned solution is a three-step train: pH correction → oxidation → filtration. This approach beats quick fixes and gives clear, low-maintenance water for homes, farms, and wineries across Cape Town, Stellenbosch, Somerset West, and the wider Western Cape.
Best-practice process (Western Cape conditions)
- Lab test first
Measure iron, manganese, pH, alkalinity, H₂S, TDS, bacteria. The result determines dosing and media choice. (Many Cape boreholes also carry manganese and sulphur odour—treat them together.) - Raise pH & add oxygen
Iron oxidises slowly at pH 6–7. Lift pH to 7.5–8.0 using a calcite contactor or soda ash (Na₂CO₃), and add air via a venturi/aeration tower. This starts converting Fe²⁺ → Fe³⁺. - Complete oxidation
For iron > ~2 mg/L or if manganese/H₂S are present, dose a controlled oxidant:
sodium hypochlorite (chlorine) for robust, all-round removal; potassium permanganate for stubborn Mn; ozone for premium systems. Include a small contact tank (5–15 minutes). - Filter on catalytic media
Use manganese-dioxide–based media (GreensandPlus, Filox, Catalox). These beds grab the oxidised iron and backwash clean.
Tip: Birm only works when pH ≥ 6.8, no chlorine, and good dissolved oxygen—great for light iron, not for mixed Fe/Mn or H₂S. - Polish & disinfect
Add GAC (taste/odour), keep a 0.2–0.5 mg/L free-chlorine residual to the house/tank, or finish with UV if you don’t want chlorine at the tap.
Sizing & maintenance notes
- Allow 10–20 W/L aeration or use a venturi on the pump line.
- Size filters at 8–12 m/h service rate; backwash at 15–25 m/h (check your pump can deliver this).
- Do annual media health checks, record entry/exit inspections, and replace worn injectors/nozzles.
Western Cape gotchas (and fixes)
- Iron bacteria: slimy fouling—shock-chlorinate, then maintain a residual.
- Manganese/H₂S: specify catalytic media and proper oxidation; don’t rely on softeners.
- Low alkalinity (common here): prefer calcite to stabilise pH and prevent corrosive water.
- RO for taste/AI: only after iron removal; pre-oxidised Fe will protect membranes.
