Typical order is pressure tank → iron/sulfur filter → water softener → optional polishing/UV. A softener can handle limited dissolved iron in some conditions, but higher iron loading can foul resin and increase salt use.
Why iron treatment commonly comes first
Removing iron upstream protects softener resin from fouling and lets the softener focus on calcium and magnesium hardness.
Manufacturer combo systems follow this pattern
SpringWell’s well-filter + salt-softener package combines dedicated iron/sulfur treatment with a downstream salt-based softener.
Low iron can be a special case
Some ion-exchange systems can handle modest dissolved iron when pH and chemistry are favorable. The manufacturer’s feed-water limits should control that decision.
Test iron and hardness together
A current well-water test prevents sizing the softener correctly for hardness while ignoring an iron load that changes the treatment design.