3M Aqua-Pure AP904
#6 in CartridgeFull review
The AP903 with scale inhibitor added, for city water that is both chlorinated and hard.
Amazon $421.18$421.18
The 3M Aqua-Pure AP904 is the better whole-house water filter overall, rated 3.1 to 2.8. The 3M Aqua-Pure AP904 leads on warranty, certification and price. The iSpring WGB32B-KSNC wins on flow. The 3M Aqua-Pure AP904 costs $218.81 less ($421.18 vs $639.99).
iSpring WGB32B-KSNC
#9 in CartridgeFull review
For homes on chloramine treated city water that want cartridges rather than a tank. Check replacement filter prices before buying.
Amazon $639.99$639.99
Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the 3M Aqua-Pure AP904 for warranty (25-year warranty vs 1-year warranty), certification (certified to NSF/ANSI 42 vs tested to NSF/ANSI 42, not certified) and price ($421.18 vs $639.99).
- Choose the iSpring WGB32B-KSNC for flow (15 gpm service flow vs 10 gpm service flow).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every cartridge whole-house water filter; a clear win is highlighted. How we rank explains each one.
| Factor weight | 3M Aqua-Pure AP904 | iSpring WGB32B-KSNC |
|---|---|---|
| Overall rating | 3.1/5 | 2.8/5 |
| Running cost 25% | 0 $3.47 per 1,000 gallons ($347.15 every 100,000 gallons) | 50 filter cost or capacity not published (neutral score used) |
| Certification 25% | 60 certified to NSF/ANSI 42 | 30 tested to NSF/ANSI 42, not certified |
| Flow 15% | 50 10 gpm service flow | 100 15 gpm service flow |
| Price 20% | 38 $421.18 | 13 $639.99 |
| Warranty 15% | 100 25-year warranty | 0 1-year warranty |
Specifications
| 3M Aqua-Pure AP904 | iSpring WGB32B-KSNC | |
|---|---|---|
| Filtration | ||
| Capacity | 100,000 gallons | 100,000 gallons |
| Replacement filters or media | $347.15 | - |
| Running cost | $3.47 per 1,000 gal | - |
| Stages | 1 | 3 |
| Certified | NSF/ANSI 42 | - |
| Tested to (not certified) | - | NSF/ANSI 42 |
| Chloramine | No | Yes |
| PFAS | No | No |
| Build | ||
| Flow | 10 gpm | 15 gpm |
| Ports | 1 in | 1 in |
| UV stage | No | No |
| Warranty | 25 years | 1 year |