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Iron Filters for Well Water
Whole house iron filters for well water — air-injection (AIO), Katalox Light, Greensand Plus and Birm systems built on Clack and Fleck valves, plus the media to rebed them. Every system ships free with a 5-year valve and 10-year tank warranty. Not sure which iron filter you need? The guide below matches the technology to your iron level, sulfur, manganese and flow rate.
How to remove iron from well water
Iron is the most common well water problem in the US, and it shows up three ways. Ferrous (clear-water) iron is dissolved: water runs clear from the tap and turns orange in the toilet tank, on fixtures and in laundry after it sits. Ferric (red-water) iron is already oxidized and arrives rusty-colored. Iron bacteria leave a slimy reddish film in the toilet tank and a swampy smell. Each one calls for a different fix, so start with a water test that gives you iron in ppm (mg/L), manganese, hydrogen sulfide, pH and hardness — send us the report and we'll size the system for free.
All whole house iron filters work the same way: oxidize the dissolved iron into a solid particle, trap it in a media bed, then backwash the bed to drain on a schedule. What differs is how they oxidize (air, a catalytic media, or chlorine) and how much iron the media can hold between backwashes. That's the whole decision.
Which iron filter technology is right for your water?
| Your water | Best technology | Why |
|---|---|---|
| Clear-water iron up to about 3 ppm, pH 6.8+, no odor | Birm | Lowest-cost media; uses dissolved oxygen already in the water. Needs no chemicals, but fails below pH 6.8 or with any hydrogen sulfide. |
| Iron 3–10 ppm, or iron + rotten-egg (sulfur) smell | Air injection (AIO) | A single tank draws in an air pocket that oxidizes iron and hydrogen sulfide together; no chemicals, no second tank. The workhorse for most well water. |
| Iron + manganese, or you want the longest media life | Katalox Light | High-capacity catalytic media that removes iron, manganese and some sulfur, works in a wider pH range, and lasts 7–10 years. |
| Iron + manganese in low-pH or low-oxygen water | Greensand Plus | Proven catalytic media, regenerated by air (AIO) or by chlorine feed; tolerates variable well conditions. |
| Iron above 10 ppm, iron bacteria, or tannins alongside iron | Chlorination + retention tank + filter | A chlorine feed kills iron bacteria and oxidizes heavy iron, the retention tank gives it contact time, and a Katalox or carbon filter removes the result. |
| Hard water with iron under about 5 ppm | Softener sized for iron | Resin will catch dissolved iron along with hardness if you oversize it and use a resin cleaner — see water softeners for iron removal. |
Iron filters for well water by situation — Clack vs. Fleck
| Situation | Clack | Fleck |
|---|---|---|
| Iron + sulfur smell (air injection) | C-Series AIO Iron & Sulfur Filter (1.25–3 cu. ft., from $1,999) | Fleck 5600 SXT AIO Iron Filter (from $1,319) · Fleck 5600 AIO Sulfur Filter (from $1,539) |
| Iron + manganese (Katalox Light) | Katalox Light Filter (from $1,279) | Fleck 2510 SXT with Katalox Light (from $1,759) |
| Iron + manganese (Greensand Plus) | Greensand Filter (from $1,074) | Fleck 2510 SXT AIO with Greensand Plus (from $1,539) |
| Light clear-water iron, no odor (Birm) | Birm Iron Filter (from $1,074) | — |
| Heavy iron or iron bacteria (chlorination) | Well water chlorination system with Stenner pump + retention tank + Katalox Light or carbon filter above | |
| Rebedding an existing iron filter | Katalox Light media · Greensand Plus media · Birm media (fits either valve) | |
Also on this page: the Pentair whole house iron reduction filter and the Crystal Quest whole house iron filter, both cartridge-free backwashing systems on their own valves.
Sizing an iron filter: flow rate matters more than home size
Iron filters are sized by two flow numbers, not by bathrooms. Service flow is what the house draws (roughly 7–10 GPM for 1–2 baths, 12–15 GPM for 3–4). Backwash flow is what your well pump must deliver to lift and clean the media — 5 GPM for a 10″ tank, 7 GPM for 12″, 10 GPM for 13″ — and it's the number most people miss. If your pump can't hit the backwash rate, the media never cleans and iron bleeds through. Check your pump's output before choosing a tank diameter; when in doubt, call 800-374-2143 with your pump horsepower and pressure-tank size.
Iron filter vs. water softener
A softener trades sodium for hardness and will also pull out clear-water iron up to about 5 ppm — but iron slowly fouls the resin, so you'll oversize it and run a resin cleaner. Above 5 ppm, with red water, sulfur or manganese, the softener needs an iron filter ahead of it. The order is always iron filter first, softener second: the filter protects the resin, and the softener finishes the hardness. Most iron-heavy wells end up with both.
What about iron in city water?
Municipal water is treated for iron, so an orange tint on city water usually means old galvanized pipe or a water-main flush, not a filter problem. Iron filters on this page are for private wells and untreated sources.
More reading: What is the best iron filter for well water? · Sulfur filters for well water · Water softeners for iron removal · Whole house filters for well water
