Iron Filter for Well Water — Types, Sizing & Costs

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.

Iron Filter Types Compared

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

Air Injection Filter

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.

Greensand Filter

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.

Birm Filter

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.

Key Installation Requirements

• Install after the pressure tank but before the water softener (if present)
• Install a sediment pre-filter to protect the iron filter media
• Ensure adequate drain for backwash water
• Size for peak flow rate, not average flow rate