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 is the better whole-house water filter overall, rated 3.4 to 2.6. The Waterdrop WHF21-PG leads on certification and price. The Waterdrop WHF21-PG costs $124.01 less ($106.98 vs $230.99).
iSpring WGB21B-PB
#11 in CartridgeFull review
For homes worried about lead pipes or with chloramine treated water. The lead claim is not certified, so test the water if lead is the main concern.
Amazon $230.99$230.99
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 Waterdrop WHF21-PG for certification (tested to NSF/ANSI 42, not certified vs no certification in a public listing, no tested to claim) and price ($106.98 vs $230.99).
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-PB |
|---|---|---|
| Overall rating | 3.4/5 | 2.6/5 |
| Running cost 25% | 50 filter cost or capacity not published (neutral score used) | 8 $2.44 per 1,000 gallons ($121.99 every 50,000 gallons) |
| Certification 25% | 30 tested to NSF/ANSI 42, not certified | 0 no certification in a public listing, no tested to claim |
| Flow 15% | 100 15 gpm service flow | 100 15 gpm service flow |
| Price 20% | 100 $106.98 | 74 $230.99 |
| Warranty 15% | 0 1-year warranty | 0 1-year warranty |
Specifications
| Waterdrop WHF21-PG | iSpring WGB21B-PB | |
|---|---|---|
| Filtration | ||
| Capacity | - | 50,000 gallons |
| Replacement filters or media | - | $121.99 |
| Running cost | - | $2.44 per 1,000 gal |
| Stages | 2 | 2 |
| Tested to (not certified) | NSF/ANSI 42 | - |
| Chloramine | No | Yes |
| PFAS | No | No |
| Build | ||
| Flow | 15 gpm | 15 gpm |
| Ports | 1 in | 1 in |
| UV stage | No | No |
| Warranty | 1 year | 1 year |