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Quick answer from a licensed plumber: For most wells with rust staining, the iSpring WGB32BM: a 5-micron sediment stage, a carbon stage and an iron and manganese cartridge that iSpring rates for up to 3.0 ppm iron and 1.0 ppm manganese, at up to 15 GPM. Add a rotten-egg smell and choose the WGB32B-MKS. Test the well first, because iron above 3 ppm and bacteria each need a different system.
Our pick for iron and manganese under 3 ppm: the iSpring WGB32BM. Check the iSpring WGB32BM on Amazon
Well water is not one problem. Iron that stains, a sulfur smell, sand and bacteria each need a different stage, and no single cartridge does all of them. So the best well water filtration system is the one that matches your test, and this page picks by what that test shows: the system for iron and manganese, the one that adds hydrogen sulfide, a backwashing unit with no iron cartridges, and a UV package for bacteria on a low-iron well. On city water, our whole house water filter picks are the better starting point.
Start With a Well Test
The EPA’s advice for private wells is to test every year for total coliform bacteria, nitrates, total dissolved solids and pH, and to test right away if the water’s odor, color or taste changes or after any repair to the well system. Use a lab certified for drinking water; your local health department may test for free. The EPA’s own chart links what you notice to what to test for:
| What you notice | EPA says test for | Where it points on this page |
|---|---|---|
| Stained fixtures or laundry | Iron, copper, manganese | WGB32BM (iron up to 3 ppm) or WCFM400K |
| Objectionable taste or smell | Hydrogen sulfide, corrosion, metals | WGB32B-MKS |
| Recurring stomach illness, or a routine coliform test | Coliform bacteria | UV: the Aquasana on a low-iron well, or a UV unit after an iron system |
| Every year, no symptoms | Total coliform bacteria, nitrates, TDS, pH | Retest; treat what the lab finds |
Well Water Filter Systems Compared
| Built for | Model | Treats | Not for | Upkeep |
|---|---|---|---|---|
| Iron and manganese | iSpring WGB32BM | Iron up to 3.0 ppm, manganese up to 1.0 ppm, sediment, chlorine | A sulfur smell; iron over 3 ppm | 3 cartridges |
| Rotten-egg smell | iSpring WGB32B-MKS | Adds hydrogen sulfide to the WGB32BM’s list (no ppm limit published) | Iron over 3 ppm | 3 cartridges |
| No iron cartridges | iSpring WCFM400K | Iron, manganese, solids, turbidity | Any hydrogen sulfide | Automatic backwash; drain and outlet |
| Bacteria, low iron | Aquasana WH-Well-CT-UVS-B | Chlorine, scale, bacteria (UV) | Iron over 0.3 ppm | Filter and UV bulb replacements; outlet |
Ratings come from iSpring and Aquasana. Every linked system was shipped or sold by Amazon, new and in stock, when we checked on September 28, 2026.
iSpring WGB32BM
3 stages: 5-micron sediment, coconut-shell carbon, iron and manganese · iron up to 3.0 ppm, manganese up to 1.0 ppm · up to 15 GPM · 1-inch NPT · 25–80 psi · 20 x 4.5-inch cartridges
Start here if your well test shows iron or manganese and your sinks, tub or laundry are staining. The third stage is iSpring’s FM25B cartridge, which iSpring rates for iron up to 3.0 ppm and manganese up to 1.0 ppm, behind a 5-micron sediment cartridge and a coconut-shell carbon block. iSpring says the catalytic media is not consumed, which is why it claims the cartridge lasts up to three times longer than greensand.
It runs on standard 20 by 4.5-inch cartridges in housings with 1-inch NPT ports, and iSpring lists a peak flow of 15 GPM and a working pressure of 25 to 80 psi. iSpring rates the sediment and carbon cartridges at up to 100,000 gallons (about 12 months) and the iron cartridge at 50,000 gallons at 3.0 ppm of iron, so on iron-heavy water the iron cartridge is the one you change first.
- Iron stage rated for up to 3.0 ppm iron and 1.0 ppm manganese (iSpring)
- Up to 15 GPM through 1-inch NPT ports
- Standard 20 x 4.5-inch cartridges
- Not rated for iron above 3.0 ppm, and not built for a rotten-egg smell
- Iron cartridge rated for half the gallons of the other two stages
- Filtration only: it does not disinfect, so a coliform result needs UV as well
Verdict: The first system to look at for a well with iron or manganese staining under 3 ppm and no sulfur smell.
iSpring WGB32B-MKS
3 stages: FP25B 5-micron sediment, FG25B-KS compound filter (lists hydrogen sulfide), FM25B iron and manganese · iron up to 3.0 ppm, manganese up to 1.0 ppm · up to 15 GPM · 1-inch NPT
This is the same housing layout and the same FM25B iron cartridge as the WGB32BM, with a different middle stage: iSpring’s FG25B-KS compound filter, which iSpring lists for hydrogen sulfide along with chlorine, chloramine, lead, mercury and heavy metals. Hydrogen sulfide is what the EPA’s well-testing chart names for an objectionable taste or smell.
iSpring rates the FG25B-KS stage for up to 150,000 gallons and the iron stage for up to 50,000 gallons at 3 ppm of iron. It does not publish a hydrogen sulfide limit for this cartridge, so a strong smell is worth a lab number before you buy. If your iron is above 3 ppm or your manganese is above 1 ppm, iSpring’s own page says to consider its higher-capacity WCFM500K system instead; we did not find that model listed on Amazon, so it is not linked here. For higher iron, see our iron filters for well water, which backwash instead of using cartridges.
- Middle stage lists hydrogen sulfide, chlorine, chloramine, lead and heavy metals (iSpring)
- Same 3.0 ppm iron and 1.0 ppm manganese rating as the WGB32BM
- Up to 15 GPM through 1-inch NPT ports
- No published hydrogen sulfide limit
- For iron above 3 ppm, iSpring points to a different, higher-capacity system
- Three cartridges on three different replacement schedules
Verdict: The pick when the well water smells like rotten eggs and also stains, as long as your iron test is at or under 3 ppm.
iSpring WCFM400K
Air injection over catalytic media · automatic backwash on an interval you set · reduces iron, manganese, solids and turbidity · media certified to NSF/ANSI 61 · not for hydrogen sulfide · drain tube and power supply included (listing)
Instead of an iron cartridge you throw away, the WCFM400K uses air injection over a catalytic media bed. iSpring says its control valve backwashes the tank to clean the media and flush the trapped iron and manganese down a drain, on an interval you set on the digital screen, and that it uses no chemicals other than air. iSpring lists the filter media as certified to NSF/ANSI Standard 61.
Two limits matter. iSpring says plainly that this system does not remove hydrogen sulfide and that hydrogen sulfide in the water would damage it; for that, iSpring points to its WCFM500K. And iSpring’s page does not publish a maximum iron level for the WCFM400K, so if your test is well above 3 ppm, get iSpring to confirm the fit before you buy. It needs a drain for the backwash and power for the valve, it stands 54 inches tall per iSpring, and iSpring recommends installing it before a water softener if you have one.
- No iron cartridges to replace; the backwash interval is adjustable (iSpring)
- Filter media certified to NSF/ANSI Standard 61, per iSpring
- Drain tube and power supply included, per the listing
- Not for water with hydrogen sulfide; iSpring warns it damages the system
- Needs a drain line and an electrical outlet
- No published maximum iron level
Verdict: The pick for a well with iron and manganese but no sulfur smell, where you would rather set a backwash schedule than buy iron cartridges.
Aquasana Rhino Well Water System with UV (WH-Well-CT-UVS-B)
20-inch pre-filter, carbon and KDF tank, salt-free scale control, 10-inch post-filter, UV · UV certified to NSF/ANSI 55 Class B (Aquasana) · 500,000 gallons or 5 years · listed for iron under 0.3 ppm
If a lab finds coliform bacteria, filtration alone is not the answer. The EPA says to contact your health department and retest when a result exceeds health standards, and it lists ultraviolet light among the ways high bacteria can be controlled. This Aquasana package pairs its Rhino carbon and copper-zinc (KDF) tank and a salt-free scale-control stage with a UV unit that Aquasana says is certified to NSF/ANSI Standard 55, Class B, plus a 20-inch pre-filter, a 10-inch post-filter and a bypass kit.
The limits are printed on the listing: Aquasana says it is best for water under 15 gpg hardness, 250 mg/L alkalinity, pH below 8.3 and iron under 0.3 ppm. That rules it out for the iron-stained wells the iSpring picks are built for. The listing rates it for 500,000 gallons or 5 years with a 5-year limited warranty, it needs no drain line or backwashing, and the UV needs a power outlet.
- UV stage certified to NSF/ANSI 55 Class B, per Aquasana
- 500,000 gallons or 5 years, with a 5-year limited warranty (listing)
- No drain line or backwashing
- Aquasana lists it for iron under 0.3 ppm
- The salt-free stage does not soften water, per Aquasana
- The UV lamp needs a power outlet
Verdict: The pick for a well that tests for bacteria but not for much iron. On an iron well, treat the iron first and put UV last.
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Add UV Last If Bacteria Shows Up
If an iron well also tests positive for coliform, treat the iron first and put a UV unit at the end of the line. The listing for the iSpring UVF55FS whole house UV filter describes it as a last step to add to a whole-house filtration system. The listing gives 1-inch MNPT connections, a 12 GPM flow rate, a 55-watt lamp with up to 9,000 hours of life, yearly lamp replacement and quartz-sleeve cleaning every 6 to 12 months. After a positive test, the EPA also says to contact your health department and retest.
What These Systems Will Not Do
- Soften water. iSpring says the WCFM400K is not a water softener, and Aquasana says its salt-free stage does not soften. For hardness, see our water softener picks, softeners for well water with iron and softener vs whole-house filter.
- Lower total dissolved solids. iSpring says its whole-house systems do not reduce TDS; that takes reverse osmosis at a sink.
- Fix a pressure problem. iSpring lists a 25 to 80 psi working range for the WGB32BM. If your pressure switch cuts out above that, see well pressure switch 30/50 vs 40/60.
Install Notes
A whole-house filter goes on the main line after the pressure tank, with shutoffs or a bypass so you can change cartridges without shutting the house down. The iSpring cartridge systems use 20 by 4.5-inch cartridges in housings with 1-inch NPT ports; if you are deciding between housing sizes, see Big Blue vs standard housings. The WCFM400K needs a drain and an outlet for its backwash, and both UV options need power. Sand and grit wear every one of these faster, so a reusable spin-down screen ahead of the system is worth adding; our sediment filters for well water page has picks, and the sediment micron guide covers the sizes. Cutting into the main line is plumbing work; if you are not comfortable doing it, have a licensed plumber install it.
FAQ
What is the best whole house water filter for well water?
It depends on your well test. For iron or manganese staining at or under 3 ppm, the iSpring WGB32BM; for the same plus a rotten-egg smell, the iSpring WGB32B-MKS; for iron with no cartridges to change, the backwashing iSpring WCFM400K; and for bacteria on a well with iron under 0.3 ppm, the Aquasana Rhino well system with UV.
Should I test my well before buying a filter?
Yes. The EPA says to test a private well every year for total coliform bacteria, nitrates, total dissolved solids and pH, and to test for iron, copper and manganese if fixtures or laundry are staining. Use a certified lab; your local health department may test for free.
How much iron can a whole house cartridge filter remove?
iSpring rates its FM25B iron cartridge, used in the WGB32BM and WGB32B-MKS, for iron up to 3.0 ppm and manganese up to 1.0 ppm. Above that, iSpring points buyers to its higher-capacity WCFM500K system.
Does a whole house filter kill bacteria in well water?
Sediment, carbon and iron cartridges filter; they do not disinfect. The EPA lists ultraviolet light among the ways to control bacteria in a well. The Amazon listing for iSpring’s UVF55FS UV unit describes it as a last step to add to a whole-house system, after the filters.
Where does a whole house filter go on a well system?
On the main line after the pressure tank, so every fixture gets filtered water, with shutoff valves or a bypass so you can change cartridges. Follow the maker on order: iSpring says to install the WCFM400K before a softener, while for its cartridge systems it suggests a softener ahead of the filter when TDS is over 300 ppm.
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 shipped or sold by Amazon, new and in stock, when we checked on September 28, 2026. 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
- iSpring: WGB32BM 3-stage iron and manganese whole house system (specifications)
- iSpring: WGB32B-MKS iron, manganese and hydrogen sulfide system
- iSpring: WCFM400K air-injection iron and manganese system
- US EPA: Protect Your Home’s Water (private well testing)
- Amazon listings for the WGB32B-MKS, WCFM400K, Aquasana WH-Well-CT-UVS-B and iSpring UVF55FS (linked above)
Bottom Line
Test the well, then buy for the result. Iron or manganese staining under 3 ppm: the iSpring WGB32BM. The same plus a sulfur smell: the WGB32B-MKS. Iron with no cartridges to change and no sulfur: the WCFM400K. Bacteria on a low-iron well: the Aquasana Rhino with UV. On an iron well that also shows bacteria, treat the iron first and add UV last.