Waterdrop G3P800
#6 in TanklessFull review
For a busy kitchen that wants fast RO water and low waste from a certified system, and can pay for it.
Amazon $849$849
The Waterdrop G3P800 is the better under-sink reverse osmosis system overall, rated 3.4 to 3.0. The Waterdrop G3P800 leads on certification. The iSpring RO800G wins on filter cost and price. The iSpring RO800G costs $390.01 less ($458.99 vs $849).
iSpring RO800G
#14 in TanklessFull review
For big households that want fast tankless RO with low waste and cheap filters. It lacks the third-party certification of pricier rivals.
Amazon $458.99$458.99
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 G3P800 for certification (certified to NSF/ANSI 58 vs no third-party certification).
- Choose the iSpring RO800G for filter cost ($85 a year in replacement filters vs $160 a year in replacement filters) and price ($458.99 vs $849).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every tankless under-sink reverse osmosis system; a clear win is highlighted. How we rank explains each one.
| Factor weight | Waterdrop G3P800 | iSpring RO800G |
|---|---|---|
| Overall rating | 3.4/5 | 3.0/5 |
| Certification 25% | 100 certified to NSF/ANSI 58 | 0 no third-party certification |
| Filter cost 20% | 28 $160 a year in replacement filters | 67 $85 a year in replacement filters |
| Water wasted 15% | 100 3:1 pure to drain | 98 2.5:1 pure to drain |
| Output 10% | 71 800 gallons a day | 71 800 gallons a day |
| Price 15% | 5 $849 | 53 $458.99 |
| Warranty 15% | 0 1-year warranty | 0 1-year warranty |
Independent measurements
Waterdrop G3P800
| Tested by | TDS reduction | Output | Pure to drain | Conditions |
|---|---|---|---|---|
| Water Filter Guru | 95.5 % | 886.5 gpd | 2.2 :1 | Tap Score lab: 776 ppm feed to 35 ppm output without remineralization (95.49%). Flow from a 12 oz fill timed at 9.14 s (0.62 gpm) with 58.3 F feed water. Ratio from a 64 oz draw (29 oz to drain); a 12 oz draw measured 1.5:1. Date is the review update date. |
iSpring RO800G
No independent test published yet.
Specifications
| Waterdrop G3P800 | iSpring RO800G | |
|---|---|---|
| Filtration | ||
| Output | 800 gallons a day | 800 gallons a day |
| Pure to drain | 3:1 | 2.5:1 |
| Stages | 10 | 2 |
| Remineralization | No | No |
| NSF/ANSI 58 | Yes | No |
| Other certifications | NSF/ANSI 42, 53 | - |
| Replacement filters | $160 a year | $85 a year |
| Build | ||
| Tank | Tankless | Tankless |
| Booster pump | Yes | Yes |
| Smart faucet | Yes | No |
| Warranty | 1 year | 1 year |