Waterdrop G5P500A
#1 in TanklessFull review
For a buyer on a budget who still wants certified RO water with minerals added back.
Amazon $229.99$229.99
The Waterdrop G5P500A is the better under-sink reverse osmosis system overall, rated 3.8 to 3.7. The Waterdrop G5P500A leads on price and filter cost. The Delta Clarifi Tankless RO wins on warranty and output. The Waterdrop G5P500A costs $569.01 less ($229.99 vs $799).
Delta Clarifi Tankless RO
#3 in TanklessFull review
For a household that wants a broadly certified tankless system with low running costs and a long warranty. Budget buyers can get similar output for less.
Amazon $799$799
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 G5P500A for price ($229.99 vs $799) and filter cost ($125 a year in replacement filters vs $201 a year in replacement filters).
- Choose the Delta Clarifi Tankless RO for warranty (5-year warranty vs 1-year warranty) and output (600 gallons a day vs 500 gallons a day).
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 G5P500A | Delta Clarifi Tankless RO |
|---|---|---|
| Overall rating | 3.8/5 | 3.7/5 |
| Certification 25% | 100 certified to NSF/ANSI 58 | 100 certified to NSF/ANSI 58 |
| Filter cost 20% | 43 $125 a year in replacement filters | 13 $201 a year in replacement filters |
| Water wasted 15% | 95 2:1 pure to drain | 95 2:1 pure to drain |
| Output 10% | 29 500 gallons a day | 43 600 gallons a day |
| Price 15% | 100 $229.99 | 9 $799 |
| Warranty 15% | 0 1-year warranty | 100 5-year warranty |
Specifications
| Waterdrop G5P500A | Delta Clarifi Tankless RO | |
|---|---|---|
| Filtration | ||
| Output | 500 gallons a day | 600 gallons a day |
| Pure to drain | 2:1 | 2:1 |
| Stages | 8 | 6 |
| Remineralization | Yes | No |
| NSF/ANSI 58 | Yes | Yes |
| Other certifications | NSF/ANSI 372 | NSF/ANSI 42, 53, 244, 372, 401 |
| Replacement filters | $125 a year | $201 a year |
| Build | ||
| Tank | Tankless | Tankless |
| Booster pump | Yes | - |
| Smart faucet | No | - |
| Warranty | 1 year | 5 years |
| Released | - | 2024 |