3M Aqua-Pure AP903
#4 in CartridgeFull review
A certified, low mess choice for city water with chlorine, for owners who would rather pay more per cartridge than handle filters.
Amazon $422.99$422.99
The 3M Aqua-Pure AP903 is the better whole-house water filter overall, rated 3.1 to 2.9. The 3M Aqua-Pure AP903 leads on warranty and certification. The iSpring WGB32B wins on flow and running cost. The iSpring WGB32B costs $2.99 less ($420 vs $422.99).
iSpring WGB32B
#7 in CartridgeFull review
For a larger house on city water that wants more carbon than a two stage system. The three filter set costs more to replace.
Amazon $420$420
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 AP903 for warranty (25-year warranty vs 1-year warranty) and certification (certified to NSF/ANSI 42 vs tested to NSF/ANSI 42, not certified).
- Choose the iSpring WGB32B for flow (15 gpm service flow vs 10 gpm service flow) and running cost ($1.15 per 1,000 gallons ($114.99 every 100,000 gallons) vs $2.45 per 1,000 gallons ($244.77 every 100,000 gallons)).
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 AP903 | iSpring WGB32B |
|---|---|---|
| Overall rating | 3.1/5 | 2.9/5 |
| Running cost 25% | 8 $2.45 per 1,000 gallons ($244.77 every 100,000 gallons) | 35 $1.15 per 1,000 gallons ($114.99 every 100,000 gallons) |
| 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 $422.99 | 38 $420 |
| Warranty 15% | 100 25-year warranty | 0 1-year warranty |
Specifications
| 3M Aqua-Pure AP903 | iSpring WGB32B | |
|---|---|---|
| Filtration | ||
| Capacity | 100,000 gallons | 100,000 gallons |
| Replacement filters or media | $244.77 | $114.99 |
| Running cost | $2.45 per 1,000 gal | $1.15 per 1,000 gal |
| Stages | 1 | 3 |
| Certified | NSF/ANSI 42 | - |
| Tested to (not certified) | - | NSF/ANSI 42 |
| Chloramine | No | No |
| PFAS | No | No |
| Build | ||
| Flow | 10 gpm | 15 gpm |
| Ports | 1 in | 1 in |
| UV stage | No | No |
| Warranty | 25 years | 1 year |