An iron filter is the most effective treatment for iron and manganese in well water — but choosing the wrong type wastes money. Here is how to match your water test results to the right iron filter.
| Filter Type | Iron Range | Also Removes | Cost Installed |
|---|---|---|---|
| Air injection (aeration) | Up to 10 mg/L | H2S, some manganese | $800–$1,500 |
| Greensand filter | Up to 10 mg/L | Manganese, H2S | $800–$1,800 |
| Birm filter | Up to 10 mg/L | Manganese (pH dependent) | $600–$1,200 |
| Chemical oxidation (H2O2) | Up to 20+ mg/L | Manganese, bacteria, H2S | $1,500–$3,000 |
| Catalytic carbon | Up to 5 mg/L | H2S, chlorine, organics | $700–$1,400 |
The most popular residential iron filter. An air pocket in the top of the filter tank oxidizes dissolved ferrous iron to ferric particles as water passes through. A bed of filter media traps the particles. The system backwashes automatically to clean the media.
Best for: Iron up to 10 mg/L, some manganese, hydrogen sulfide. Requires no chemical addition. Low operating cost.
Uses a manganese-dioxide-coated media (greensand) that catalyzes oxidation of iron and manganese. Requires potassium permanganate or chlorine to regenerate the media. Highly effective for iron/manganese combinations.
Best for: Iron and manganese together, especially at moderate-high levels. Requires ongoing chemical supply.
Catalytic media that works similarly to greensand but without chemical regeneration — uses dissolved oxygen in the water to oxidize iron. Works well when pH is above 6.8 and dissolved oxygen is adequate.
Best for: Lower iron levels (under 5 mg/L) with adequate pH and oxygen. Lowest operating cost of any iron filter.
Test for iron type before buying. Dissolved ferrous iron, particulate ferric iron, colloidal iron, and iron bacteria each respond differently to treatment. A comprehensive water test tells you which type you have and at what level — this determines which filter is most effective for your specific water.
A greensand filter is the most effective choice for iron and manganese together, especially at moderate-high levels. It uses manganese-dioxide-coated media to catalyze oxidation, though it requires ongoing potassium permanganate or chlorine to regenerate.
A birm filter has the lowest operating cost of any iron filter type since it uses dissolved oxygen in the water to oxidize iron rather than chemical regeneration. It works best for lower iron levels (under 5 mg/L) with pH above 6.8 and adequate dissolved oxygen.
Chemical oxidation using hydrogen peroxide (H2O2) handles the highest range, treating iron up to 20+ mg/L, and also addresses manganese, bacteria, and hydrogen sulfide — though it costs more, typically $1,500-$3,000 installed.
No — an air injection (aeration) filter oxidizes dissolved ferrous iron using an air pocket in the filter tank rather than chemical addition, making it a popular choice with low operating costs for iron up to 10 mg/L.
Install it after the pressure tank so it treats water at consistent pressure, and before any other treatment equipment like a water softener, since iron can clog softener resin if it's not removed first.
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