Waterdrop TK-FS
The Waterdrop with fluoride filters in the box. Costs $80 more than the TK-A, which can take fluoride filters as an add-on.
Amazon $239.99$239.99
The Waterdrop TK-FS and the Purewell SF-2.25G PFAS-Free 6-Stage are evenly matched, rated 3.3 and 3.2. The Waterdrop TK-FS leads on certification. The Purewell SF-2.25G PFAS-Free 6-Stage wins on value. The Purewell SF-2.25G PFAS-Free 6-Stage costs $71 less ($168.99 vs $239.99).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Purewell SF-2.25G PFAS-Free 6-Stage
The Purewell to pick when PFAS and lead are the concern. It uses a different filter than the other Purewells.
Amazon $168.99$168.99
Which should you buy?
- Choose the Waterdrop TK-FS for certification (states certification to NSF/ANSI 42, NSF/ANSI 372 vs states certification to NSF/ANSI 42).
- Choose the Purewell SF-2.25G PFAS-Free 6-Stage for value ($75.11 per gallon of capacity ($168.99, 2.2 gal) vs $106.66 per gallon of capacity ($239.99, 2.2 gal)).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every up to 2.25 gal gravity water filter; a clear win is highlighted. How we rank explains each one.
| Factor weight | Waterdrop TK-FS | Purewell SF-2.25G PFAS-Free 6-Stage |
|---|---|---|
| Overall rating | 3.3/5 | 3.2/5 |
| Value 25% | 53 $106.66 per gallon of capacity ($239.99, 2.2 gal) | 75 $75.11 per gallon of capacity ($168.99, 2.2 gal) |
| Running cost 15% | 75 $0.012 per gallon filtered ($34.99 per element, 3,000 gal each) | 50 replacement cost or element life not published (neutral score used) |
| Capacity 15% | 17 2.2 gal tank | 17 2.2 gal tank |
| Certification 20% | 40 states certification to NSF/ANSI 42, NSF/ANSI 372 | 30 states certification to NSF/ANSI 42 |
| Element life 15% | 100 3,000 gal rated per element | 100 3,000 gal rated per element |
| Warranty 10% | 11 1-year warranty | 0 warranty not published, scored as none |
Specifications
| Waterdrop TK-FS | Purewell SF-2.25G PFAS-Free 6-Stage | |
|---|---|---|
| Capacity and flow | ||
| Tank capacity | 2.2 gal | 2.2 gal |
| Price per gallon of capacity | $106.66 | $75.11 |
| Elements included | 4 | - |
| Maximum elements | 4 | - |
| Filtration | ||
| Element type | Coconut shell carbon filter (black) | 6-stage filter: mesh, PP cotton, carbon, KDF and silver ions (ZeroWater-compatible) |
| Certified | NSF/ANSI 42, NSF/ANSI 372 | NSF/ANSI 42 |
| Certification detail | Listing: system certified to NSF/ANSI 372 and the black carbon filter to NSF/ANSI 42. The listing does not say the fluoride filters are certified. | Listing: IAPMO certified to reduce Total PFAS, lead, chlorine and mercury; the filter is NSF/ANSI 42 certified. Does not reduce TDS. |
| Fluoride | Included | - |
| Fluoride element life | 1,000 gal | - |
| Running cost | ||
| Rated life per element | 3,000 gal each | 3,000 gal each |
| Replacement element | 35 $ | - |
| Cost per gallon filtered | $0.012 | - |
| Build | ||
| Material | 304 stainless steel | 304 stainless steel |
| Height | - | 20 in |
| Diameter | - | 8.8 in |
| Weight | - | 7.7 lb |
| Warranty | 1 year | - |