An iron and manganese filter removes the two metals that stain a house orange and black. Which filter you need depends almost entirely on the form the metal arrives in: dissolved and invisible at the tap, already oxidized into rust particles, or bound up with bacteria in a slime. Test first, then buy.
Why both metals travel together
Iron and manganese come out of the same rock and behave in similar ways, which is why almost every filter sold for one handles the other. Both carry secondary standards, meaning the concerns are aesthetic rather than health-based: the recommended maximums are 0.3 mg/L for iron and 0.05 mg/L for manganese. Manganese is the one people underestimate. It shows at far lower levels than iron does, and it is what produces the black specks in the toilet tank and the gray cast on white laundry, so a filter sized only on the iron result will often leave the manganese complaint unresolved.
Oxidizing filters: the mainstream choice
The workhorse for a well is a single tank of catalytic media with a backwashing valve. Air, or a small injected dose of chlorine or peroxide, converts the dissolved metals into solid particles, and the media bed catches those particles until the nightly backwash flushes them to drain. Air injection systems draw a pocket of air into the top of the tank on each cycle and need no chemical at all, which is why they are the common recommendation for a family well. Chemical injection is chosen when levels are high, when sulfur is present alongside the iron, or when iron bacteria are in play and the household needs the disinfecting effect as well.
When a softener can do the job instead
A water softener will hold back dissolved iron under the right conditions, and for a house with modest iron and real hardness that is the tidiest single-tank answer. The conditions are specific: pH above 6.7, hardness between 3 and 20 grains per gallon, and dissolved iron under 5 mg/L. Outside that window the softener is the wrong tool. The trap is oxidized iron, the rust-colored particles you can already see in a glass of standing water: those foul the resin bed rather than exchange onto it, and a fouled softener loses capacity, channels and eventually needs the resin replaced.
Testing before you spend
Ask the lab for iron, manganese, pH, hardness and hydrogen sulfide, and get the sample right. Iron oxidizes on standing, so a bottle filled and left on a counter overnight will tell you the total but not how much was dissolved when it left the well. If the water is clear at the tap and turns orange in the glass over an hour, you have dissolved iron. If it is already colored at the tap, it is oxidized. If there is a reddish slime in the toilet tank or the pressure tank, suspect iron bacteria, which needs shock chlorination as well as filtration. Our well water testing guide sets out the sampling routine.
Questions people ask about iron and manganese filter
Is iron in well water a health problem?
Iron and manganese carry secondary standards, which are aesthetic rather than health-based, so the case for treating them is staining, taste and appliance damage rather than a health limit.
Why is my laundry gray rather than orange?
That points at manganese rather than iron. Manganese shows as black or gray staining and appears at much lower concentrations than iron does, so it is often missed on a test that only asked for iron.
Will a sediment filter catch iron?
Only iron that has already oxidized into particles large enough to strain out. Dissolved iron passes straight through a sediment cartridge and oxidizes afterwards, staining the fixtures downstream.
How often does an iron filter backwash?
Most household units backwash on a nightly or every-other-night schedule set at the valve. It needs a drain of adequate capacity and a supply that can deliver the backwash flow rate.
Do I put the iron filter before or after the softener?
Before. Removing iron ahead of the softener protects the resin from fouling, which is the most common way a softener on well water is ruined.