What iron level requires a dedicated iron filter?

Dedicated iron filtration is generally recommended above ~1.0 ppm iron. Softerners can sometimes polish trace ferrous iron below ~1.0 ppm, but an iron filter is the best practice for sustained performance.

Do I need to fix pH before iron removal?

Often yes. Many oxidation media perform best when pH is near neutral (≥6.8–7.0). If your pH is low, add a neutralizer ahead of the iron filter.

How much backwash flow do I need?

Typical targets: 10×54 tanks need about 6–7 GPM; 12×52 need 8–10 GPM; 13×54 need 10–12 GPM. Always verify the media’s spec sheet and your well’s actual flow.

What if I have sulfur (rotten egg) odor too?

Use oxidation (air, peroxide, or chlorine) ahead of a catalytic carbon filter. Strong H2S typically requires a continuous oxidant feed or air-injection system.

Can I treat manganese with the iron filter?

Yes, with proper oxidation and contact time. Even low manganese (≥0.05 ppm) should be addressed to prevent staining.

Well Water Iron Filter Calculator | WaterSoftenerPlus

Well Water Iron Filter Calculator

Enter your water test values to get a recommended treatment path, media, and tank/backwash guidance. PPM = mg/L.

Helpful links: Water Treatment Atlas • Contact Us • Shipping • Returns

Enter Your Water Data

Iron (Fe) — ppm

If iron changes water color when exposed to air, choose the right “iron form” below.

Manganese (Mn) — ppm

Treat even at low levels (>0.05 ppm) for staining risk.

Many oxidation media prefer pH ≥ 6.8–7.0. Low pH often needs neutralization first.

Iron Form

Hydrogen Sulfide (H₂S / “rotten egg” smell)

H₂S needs oxidation (air, peroxide, chlorine) and often catalytic carbon polishing.

Available Backwash Flow — GPM

Use your well/pump’s actual flow. This determines permissible tank sizes.

Hardness (grains) — optional

Softener is separate from iron filter; it can polish trace ferrous iron (<1 ppm) in some cases.

People in Home (for sizing)

Summary & Treatment Path

Fill in the form and click “Calculate Recommendation.”

Suggested Media & Tank Options

Backwash & Tank Size Guide (Typical)

These are common requirements. Always verify the exact media’s spec sheet.

10×54 tank → needs ~6–7 GPM backwash
12×52 tank → needs ~8–10 GPM backwash
13×54 tank → needs ~10–12 GPM backwash

If your well can’t supply the required backwash, choose a smaller tank or a lighter media, or consider dual units in alternating service.

For heavy commercial or high-flow applications, see Control Valves or our Water Treatment Atlas.

What the Calculator Considers

Iron & manganese concentration, and whether iron is ferrous (clear) or ferric (oxidized)
pH suitability for oxidation media (neutralization if low)
Presence/strength of H₂S (“rotten egg” smell)
Available backwash flow (critical for bed lift and cleaning)
Household size as a proxy for service flow demand

Tip: Get a recent lab test for accurate Fe/Mn/pH/H₂S. Field strips are okay for screening but not for final design.

Need Help?

We can sanity-check your numbers and recommend a complete kit (valve, tank, media) that matches your well and plumbing.

Get Help Sizing

Last updated: October 30, 2025