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Quick answer from a licensed plumber: For a well with clear water iron up to about 6 ppm, buy the AFWFilters Iron Pro 2: fine mesh resin on a Fleck 5600SXT metered valve, with AFWFilters stating ferrous iron up to 6 ppm and saying plainly that red water iron needs a separate iron filter. Test the well first. No softener here is rated for rusty red water.
Our pick for most wells with iron: the AFWFilters Iron Pro 2. Check the AFWFilters Iron Pro 2 on Amazon
Well water changes what a softener has to do. City water is mostly a hardness problem. A well can add iron, manganese, sediment and a pump that sets your pressure and flow. Every softener here removes hardness. What separates them is how much iron each maker says it handles, and what its own manual says happens past that point. If you are on city water, start with our best water softener guide instead.
Water Softeners for Well Water Compared
| Softener | Grain capacity | Iron, as the maker states it | Flow and pressure, per maker documents | Sediment pre-filter |
|---|---|---|---|---|
| AFWFilters Iron Pro 2 | 64,000 (48,000 also) | Ferrous iron up to 6 ppm (AFWFilters) | Valve alone 20 gpm, 20–125 psi (Pentair); no system rating | Not stated |
| Aquasure Harmony fine mesh | 32,000 | Up to 10 ppm (Aquasure page); no limit in manual | Not published; 25–125 psi (manual) | Not stated |
| Kenmore 350 | 32,000 | Clear water iron up to 8 ppm (Kenmore) | 8.0 gpm rated, 3 gpm minimum; 20–125 psi (350 Series manual) | Built-in screen |
| iSpring WCS45KG | 45,000 | No rating; iron filter first (iSpring page) | 8 GPM rated, 26 GPM peak; 20–50 psi (manual) | None built in |
Figures come from each maker’s product page and manual. Each linked softener was listed in stock on Amazon when we checked on September 28, 2026. AFWFilters and Aquasure USA sell their own units; the Kenmore 350 and the iSpring WCS45KG are sold by Amazon.
AFWFilters Iron Pro 2 Softener and Iron Filter
64,000 grain (48,000 also linked) · fine mesh resin in a Pentair tank · Fleck 5600SXT digital metered valve · ferrous iron up to 6 ppm, manganese up to 6 ppm (AFWFilters) · bypass valve, brine tank with safety float, 1-inch male connections · 5-year valve and 10-year tank warranty per the Amazon listing
The Iron Pro 2 is AFWFilters’ own combination of fine mesh resin and a Fleck 5600SXT metered valve. AFWFilters says the resin removes ferrous iron up to 6 ppm, and the Amazon listing for the 64,000-grain unit adds manganese up to 6 ppm. Its product page also draws the line most listings blur. Ferrous iron is the kind that looks clear at the tap. For ferric iron, the kind that comes out rust-colored, AFWFilters says fine mesh resin is “NOT recommended” and a dedicated iron filter is.
The Fleck valve is the same one many installers use, and Pentair publishes its numbers. For the valve alone, Pentair rates 20 gpm continuous at a 15 psi drop, a maximum backwash of 7 gpm, and a working pressure of 20 to 125 psi. Those are valve figures, not a system flow rating, and AFWFilters does not publish a system flow on the pages we read. AFWFilters also gives the sizing rule for iron: add 4 grains of compensated hardness for each ppm of iron and manganese. The 48,000-grain listing is linked as well; it states iron as a 4 to 7 ppm range and says it treats up to 14 GPM, both less exact than the 6 ppm on the 64,000-grain page.
- Fine mesh resin with a stated ferrous iron limit of 6 ppm (AFWFilters)
- AFWFilters says plainly that ferric (red-water) iron needs a dedicated iron filter
- Fleck 5600SXT metered valve with a published spec sheet from Pentair
- Bypass valve and brine tank included; 10-year tank warranty per the listing
- No system service flow rate on the pages we read; the Fleck figures are for the valve alone
- A full-size system of valve, tank and brine tank, so the install is bigger than a cabinet unit
- The 48,000-grain listing gives iron as a 4 to 7 ppm range, not one number
- Needs a drain, and a sediment filter ahead of it if the well carries sand
Verdict: The pick for a well with clear-water iron in the low single digits and room for a full-size system with a drain.
Aquasure Harmony 32,000 Grain Softener With Fine Mesh Resin
32,000 grain · Aquatrol digital metered head · pre-filled fine mesh resin · bypass valve and 1-inch NPT male adapters · households up to 4 people (Aquasure) · feed water 25–125 psi, up to 100°F (owner’s manual) · 5-year warranty with registration, 2 years without (manual)
Aquasure says the fine mesh resin in this Harmony model is designed to remove “up to 10ppm of iron commonly found in well water.” That is the highest iron figure of the four picks, and it is the maker’s marketing claim. The owner’s manual, which covers the whole Harmony line including the fine mesh models, gives no iron limit. Its warranty says resin and internal valve parts “will not be covered for systems used to remove iron, manganese” or very high chlorine. So the 10 ppm claim and the warranty do not line up, and we would not plan a well around 10 ppm.
The manual is useful on wells. It says to power off the well pump before closing the main, and to place the softener as close as possible to the pressure tank. Its sizing formula is (grain capacity ÷ hardness) − (people × 75 gallons); the worked example is 32,000 grains at 25 grains per gallon for 3 people, which gives 1,055 gallons. The feed pressure range is 25 to 125 psi, so a 30/50 well switch clears the minimum at cut-in. Aquasure does not publish a rated service flow on the pages we read. The 48,000-grain fine mesh model was out of stock on Amazon when we checked, so only the 32,000-grain size is linked.
- Highest maker iron claim of the four: up to 10 ppm (Aquasure)
- Ships pre-filled, with bypass valve and 1-inch NPT male adapters (Amazon listing)
- Manual gives a worked sizing formula and a 25–125 psi feed pressure range
- Manual covers wells: pump off first, softener near the pressure tank
- The 10 ppm figure is marketing; the manual gives no iron limit
- Manual says resin and valve parts are not covered when used to remove iron or manganese
- No rated service flow on the pages we read
- Only the 32,000-grain size is in stock to link; that is sized for up to 4 people
Verdict: The pick if you want the largest stated iron margin and a small, pre-filled unit, as long as you treat 10 ppm as a claim, not a plan.
Kenmore 350 Water Softener (32,000 Grain)
32,000 grain · households of 1 to 4 · hardness up to 90 gpg and clear water iron up to 8 ppm (Kenmore) · high-flow 3/4-inch valve · built-in screen for large particles · bypass valve and installation kit included · 1 year parts and labor, 3 years electronics, 10 years tank (Kenmore)
Kenmore states the 350 reduces hardness up to 90 grains per gallon and clear water iron up to 8 ppm, and calls it compatible with private well water. Its 350 Series owner’s manual (model 625.383560, the version we could read) is more careful. It says a softener will not remove red water iron, that iron over the unit’s clear-water maximum needs an iron filter, and that with any clear-water iron the resin bed should be cleaned at least every 6 months. It also notes that the State of Wisconsin requires additional treatment above 5 ppm of clear water iron. Our read: 8 ppm is the ceiling, and a well near 5 ppm should get an iron filter.
The manual gives the numbers a well owner needs. Rated service flow is 8.0 gpm at a 14 psi pressure drop, feed pressure is 20 to 125 psi, and the house needs at least 3 gpm, with a bucket test using two open faucets to check it. For wells it says to install the softener after the pressure tank and to place an iron filter upstream of the softener. Drain tubing is 3/8-inch inside diameter with an air gap of about 1-1/2 inches. The manual is for an older 350 Series model, so check the one that comes in the box.
- Clear water iron up to 8 ppm and hardness up to 90 gpg, as stated by Kenmore
- Sold by Amazon
- Built-in screen for large particles; bypass valve and installation kit included (Kenmore)
- Manual gives a 3 gpm minimum flow and a bucket test to check it
- Clear-water iron only; the manual says it will not remove red water iron
- 8 ppm is Kenmore’s figure; the manual points to a 5 ppm line for extra treatment
- Sized for 1 to 4 people, small for a big house with hard, iron-heavy water
- The manual we could read is for an older 350 Series model
Verdict: The pick for a smaller household on a well with light clear-water iron, when you want the unit sold by Amazon.
iSpring WCS45KG 45,000 Grain Softener
45,000 grain · one-tank design · rated service flow 8 GPM, peak 26 GPM · working pressure 20–50 psi · 1-inch NPT · 33.8–102.2°F · no built-in sediment filter · 120 V adapter · 1-year warranty (iSpring)
iSpring is the one pick here that gives no iron rating. Its product page says the softener has no built-in sediment filter and recommends a pre-filter if the water carries a lot of sediment. It also says iron “would negatively impact the effectiveness” of the softener and recommends an iron filter first if there is iron in the water. The manual is more permissive. It has an Iron & Manganese salt setting, says to add 4 grains per gallon for every 1 ppm of ferrous iron, and says to pick the WELL setting if any iron or manganese is present or the water is cloudy, which makes the unit backwash every time. Page and manual do not agree, and we treat the page as the limit.
The catch on a well is pressure. iSpring’s manual gives a working pressure of 20 to 50 psi, and says to fit a pressure reducing valve above 50 psi and a booster pump below 20. A 30/50 switch peaks right at that limit, and a 40/60 switch cuts out 10 psi over it (our arithmetic). See well pressure switch 30/50 vs 40/60. The rated flow is 8 GPM with a 26 GPM peak, and the manual says the flow should be low for better softening.
- 45,000-grain capacity in one tank (iSpring)
- Rated service flow (8 GPM) and peak flow (26 GPM) are published in the manual
- Manual has a WELL water setting and gives 4 grains per ppm of ferrous iron
- Sold by Amazon
- iSpring’s page says to put an iron filter first if the water has iron, and gives no iron ppm rating
- Working pressure is 20–50 psi, so a 40/60 well switch needs a pressure reducing valve
- No built-in sediment filter
- Weighs 120 lb, per iSpring
Verdict: The pick for a hard well that tests clean on iron, sediment and pressure, where you want the biggest tank of the four.
I send an occasional note when a new guide goes up — repairs worth doing yourself, and the parts that actually last. No spam, no course funnel; written by a licensed Georgia plumber.
Iron Limits: What the Makers Say, and What Happens Above Them
“Iron removal” on a softener means clear water (ferrous) iron, dissolved in the water. It looks clear coming out of the tap and turns cloudy or rust-colored in a glass after 15 to 30 minutes, per Kenmore’s manual. Red water (ferric) iron is already solid and rust-colored at the tap, and it will clog a softener bed. EPA lists iron at 0.3 mg/L and manganese at 0.05 mg/L as secondary guidance levels for rusty color, staining and metallic taste, so small amounts already show up in laundry and fixtures.
| Softener or valve | Stated iron limit | What the maker says above it |
|---|---|---|
| AFWFilters Iron Pro 2 | Ferrous iron up to 6 ppm; manganese up to 6 ppm (64,000-grain listing) | Ferric iron: fine mesh resin “NOT recommended,” use a dedicated iron filter (AFWFilters) |
| Aquasure Harmony fine mesh | Up to 10 ppm (Aquasure product page); no limit in the manual | Manual: resin and valve parts not covered when used to remove iron or manganese |
| Kenmore 350 | Clear water iron up to 8 ppm (Kenmore); manual cites Wisconsin’s 5 ppm line | Red water iron or iron over the maximum needs an iron filter; clean the resin bed at least every 6 months (manual) |
| iSpring WCS45KG | No ppm rating; iron filter recommended first (product page) | Manual adds 4 grains per ppm of ferrous iron and an Iron & Manganese setting |
| Fleck 5600SXT valve (Pentair) | No iron rating for the valve | Manual: iron-clogged piping needs a separate iron filter ahead; iron in softened water points to a fouled bed, so add mineral cleaner and regenerate more often |
Two patterns show up. Makers rate limits for clear water iron only, and every manual sends red water iron to a separate iron filter. For that filter, see our whole house filters for well water or our iron filters for well water. Water that smells like sulfur or leaves slime points to bacteria, which no softener here is built to treat.
How to Size a Softener for Well Water
Start with three numbers from a water test: hardness in grains per gallon, iron in ppm, and manganese. If your report gives hardness in mg/L, Aquasure’s manual says to divide by 17.1 to get grains per gallon. Then add the iron. Iron loads the resin like extra hardness, and the makers give different factors: 4 grains per ppm of iron and manganese (AFWFilters), 4 per ppm of ferrous iron (iSpring), and 5 per ppm (Kenmore’s manual). We use 5, which errs toward regenerating early. The Fleck control then works out capacity as unit capacity divided by feed water hardness, less a reserve, and Aquasure’s formula subtracts 75 gallons per person.
Example (our arithmetic): hardness 12 grains per gallon, iron 2 ppm, 4 people. Compensated hardness = 12 + (5 × 2) = 22 grains per gallon. A 32,000-grain unit treats 32,000 ÷ 22 = 1,455 gallons per regeneration. Aquasure’s deduction is 4 people × 75 gallons = 300, so the program value is 1,455 − 300 = 1,155 gallons. At 300 gallons a day that is about 4 days between regenerations. A 64,000-grain unit gives 2,909 − 300 = 2,609 gallons, about 8 to 9 days.
The table shows what iron does to a 32,000-grain and a 64,000-grain softener on 12 grains of hardness, before any reserve (our arithmetic).
| Iron | Compensated hardness (5 grains per ppm) | Gallons per regeneration, 32,000 grain | Gallons per regeneration, 64,000 grain |
|---|---|---|---|
| 0 ppm | 12 gpg | 2,667 | 5,333 |
| 1 ppm | 17 gpg | 1,882 | 3,765 |
| 2 ppm | 22 gpg | 1,455 | 2,909 |
| 4 ppm | 32 gpg | 1,000 | 2,000 |
| 6 ppm | 42 gpg | 762 | 1,524 |
One caution on the grain number. It is a nominal size. Kenmore’s older 350 Series manual lists 14,200 grains at 2.8 lb of salt, 29,900 at 8.8 lb and 35,600 at 14.7 lb for a unit sold as 32,000 grain, so real capacity moves with the salt setting. For more on resin volume, see our guide to resin by tank size.
Before You Buy
- Test the well first. EPA says to test a private well every year for total coliform bacteria, nitrates, total dissolved solids and pH. For a softener you also need hardness, iron (clear or red) and manganese. Kenmore’s manual says to have the water tested to pick the right equipment. See the water hardness scale.
- Check your flow. Kenmore says a flow of at least 3 gpm is needed, and gives a bucket test: open two cold faucets near where water enters the house and time how long it takes to fill a gallon. Then compare the softener’s rated flow with what runs at once in your house and with your pump’s output. Kenmore and iSpring both rate 8 gpm; Pentair rates the Fleck valve alone at 20 gpm.
- Check your pressure range. A 30/50 switch cycles between 30 and 50 psi and a 40/60 between 40 and 60. iSpring allows 20–50 psi, Kenmore and the Fleck valve 20–125 psi, and Aquasure 25–125 psi. See well pressure switch 30/50 vs 40/60.
- Plan the order. Kenmore’s manual puts the softener after the pressure tank and before the water heater, with an iron filter upstream of the softener. iSpring recommends a sediment pre-filter when the water carries sediment; see our sediment filters for well water and 5 vs 20 micron guide.
- Protect the heater. Kenmore says water into the softener must not exceed 120°F. iSpring says to keep at least 3 meters of pipe between the softener outlet and the water heater inlet, or add a check valve.
Install Notes for a Well System
Bypass. Pentair says to always fit a bypass valve if the unit does not have one. Kenmore says the same and to leave it in the service position except for repairs. All four picks ship with a bypass or list one.
Drain line. Pentair says the residential drain line should be at least 1/2 inch, and 3/4 inch if backwash flow is over 7 gpm or the run is over 20 feet, with an air gap of twice the pipe diameter and at least 1 inch. Aquasure says at least 1/2 inch, 3/4 inch past 20 feet, no sags, and an air gap of at least 1.5 inches. Kenmore uses 3/8-inch inside-diameter tubing with a 1-1/2 inch gap, and says the softener will not work if the hose is pinched or restricted. iSpring says the overflow pipe and the drain must each go to the sewer separately, not be combined.
Brine line and salt. The brine line runs from the brine tank to the brine port on the valve, per Aquasure and iSpring. Pentair’s manual has a brine line flow controller size to record at install. See why a softener stops regenerating if it stalls later.
Well-specific traps. Aquasure says to power off the well pump and then close the main before you cut in. Pentair lists air in a well system as a cause of resin loss down the drain and says to make sure the well has a proper air eliminator. Iron builds up in a bed, so Pentair says to add mineral cleaner and regenerate more often if iron shows up in softened water, and Kenmore says to clean the bed every 6 months with clear water iron. Installation costs are in our water softener installation guide.
FAQ
What is the best water softener for well water with iron?
One with fine mesh resin and a stated iron limit that matches your test. AFWFilters states ferrous iron up to 6 ppm for the Iron Pro 2, Aquasure claims up to 10 ppm for its fine mesh Harmony, and Kenmore states 8 ppm of clear water iron for the 350. Above the limit, or with red water iron, put an iron filter ahead of the softener.
How do I size a water softener for well water?
Add 4 to 5 grains to your hardness for every ppm of iron, then divide the grain capacity by that number. AFWFilters and iSpring use 4 grains per ppm and Kenmore uses 5. Aquasure’s formula then subtracts 75 gallons per person. With 12 grains of hardness and 2 ppm of iron, a 32,000-grain unit treats about 1,455 gallons between regenerations (our arithmetic).
Will a water softener remove red or rusty iron?
No, not reliably. Kenmore says a softener will not remove red water iron, and AFWFilters says fine mesh resin is not recommended for ferric iron and a dedicated iron filter is. Clear water iron turns cloudy or rust-colored after 15 to 30 minutes in a glass, per Kenmore, and that is the kind a softener can handle in limited amounts.
Do I need a sediment filter and an iron filter ahead of a softener?
Often, yes. Kenmore says to always place an iron filter upstream of a softener, and to install the softener after the pressure tank. iSpring says its softener has no built-in sediment filter and recommends a pre-filter when the water carries sediment. Test first, then add only what the test calls for.
Will my well pump and pressure switch work with a softener?
Check three numbers. Kenmore says the house needs at least 3 gpm, and its rated service flow is 8.0 gpm. iSpring rates 20 to 50 psi, so a 40/60 switch needs a pressure reducing valve, while Aquasure allows 25 to 125 psi and the Fleck valve 20 to 125 psi. Compare your pump output and switch setting with the softener you pick.
Why Trust Plumbing Picks
Plumbing Picks is written by a licensed Georgia journeyman plumber. Every size, rating, dimension and spec on this page comes from the manufacturer pages and documents listed below, which we opened and read, or from the Amazon listing we link; nothing here comes from hands-on testing. Each linked product was listed new and in stock on September 28, 2026, and was sold by Amazon or by the maker’s own Amazon storefront (AFWFilters, Aquasure USA). Where a link goes to Amazon we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.
Sources
- AFWFilters: Iron Pro 2 64,000-grain combination softener and iron filter (product page)
- Pentair: Fleck 5600SXT high performance control valve specification sheet 42749 (Rev D)
- Pentair: Fleck 5600SXT downflow service manual 42684
- Aquasure USA: Harmony Series 32,000-grain softener with fine mesh resin (product page)
- Aquasure: Harmony Series whole house water softener owner’s manual (models AS-HS32D to AS-HS64FM)
- Kenmore Water Solutions: Kenmore 350 water softener (product page)
- Kenmore: IntelliSoft 350 Series owner’s manual, model 625.383560
- iSpring: WCS45KG whole house water softener (product page)
- iSpring: WCS45KG installation instructions and user manual
- US EPA: Protect Your Home’s Water (private well testing)
- US EPA: Secondary Drinking Water Standards, guidance for nuisance chemicals
- Amazon listings for the AFWFilters Iron Pro 2, Aquasure Harmony 32,000-grain fine mesh, Kenmore 350 and iSpring WCS45KG (linked above)
Bottom Line
Test the well, then buy to the iron number. The AFWFilters Iron Pro 2 is the pick for clear water iron up to 6 ppm. The Aquasure Harmony fine mesh claims 10 ppm but its manual will not stand behind it, so treat that as a ceiling. The Kenmore 350 suits a small household with light iron, and the iSpring WCS45KG suits hard water without iron. Size with iron added to your hardness, check your pump flow and pressure switch against the rating, and put an iron filter ahead of any softener if the water runs red.