Waterdrop WHF21-PG
#1 in CartridgeFull review
A low cost starter system for chlorinated city water in a small home.
Amazon $106.98$106.98
The Waterdrop WHF21-PG and the iSpring WGB21B are evenly matched, rated 3.4 and 3.4. The Waterdrop WHF21-PG costs $49.01 less ($106.98 vs $155.99).
iSpring WGB21B
#2 in CartridgeFull review
A low cost first whole-house filter for city water with chlorine taste. Expect to change filters several times a year.
Amazon $155.99$155.99
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.
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 | Waterdrop WHF21-PG | iSpring WGB21B |
|---|---|---|
| Overall rating | 3.4/5 | 3.4/5 |
| Running cost 25% | 50 filter cost or capacity not published (neutral score used) | 44 $0.90 per 1,000 gallons ($45.11 every 50,000 gallons) |
| Certification 25% | 30 tested to NSF/ANSI 42, not certified | 30 tested to NSF/ANSI 42, not certified |
| Flow 15% | 100 15 gpm service flow | 100 15 gpm service flow |
| Price 20% | 100 $106.98 | 98 $155.99 |
| Warranty 15% | 0 1-year warranty | 0 1-year warranty |
Specifications
| Waterdrop WHF21-PG | iSpring WGB21B | |
|---|---|---|
| Filtration | ||
| Capacity | - | 50,000 gallons |
| Replacement filters or media | - | $45.11 |
| Running cost | - | $0.90 per 1,000 gal |
| Stages | 2 | 2 |
| Tested to (not certified) | NSF/ANSI 42 | NSF/ANSI 42 |
| Chloramine | No | No |
| PFAS | No | No |
| Build | ||
| Flow | 15 gpm | 15 gpm |
| Ports | 1 in | 1 in |
| UV stage | No | No |
| Warranty | 1 year | 1 year |