Aquasana HealthShield RO
#9 in TanklessFull review
For a buyer who wants the broadest certification in a fast tankless system and doesn’t mind the price. Most households get similar output for much less elsewhere.
Amazon $1,299.99$1,299.99
The Aquasana HealthShield RO is the better under-sink reverse osmosis system overall, rated 3.2 to 3.1. The Aquasana HealthShield RO leads on certification. The Frizzlife PD800-TAM4 wins on filter cost and price. The Frizzlife PD800-TAM4 costs $790.01 less ($509.98 vs $1,299.99).
Frizzlife PD800-TAM4
#12 in TanklessFull review
For a household that wants fast mineralized RO water with low filter costs and does not need NSF 58 certification.
Amazon $509.98$509.98
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 Aquasana HealthShield RO for certification (certified to NSF/ANSI 58 vs not certified to NSF/ANSI 58; certified to NSF/ANSI 372).
- Choose the Frizzlife PD800-TAM4 for filter cost ($119 a year in replacement filters vs $350 a year in replacement filters) and price ($509.98 vs $1,299.99).
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 | Aquasana HealthShield RO | Frizzlife PD800-TAM4 |
|---|---|---|
| Overall rating | 3.2/5 | 3.1/5 |
| Certification 25% | 100 certified to NSF/ANSI 58 | 30 not certified to NSF/ANSI 58; certified to NSF/ANSI 372 |
| Filter cost 20% | 0 $350 a year in replacement filters | 46 $119 a year in replacement filters |
| Water wasted 15% | 94 1.8:1 pure to drain | 95 2:1 pure to drain |
| Output 10% | 71 800 gallons a day | 71 800 gallons a day |
| Price 15% | 0 $1,299.99 | 44 $509.98 |
| Warranty 15% | 25 2-year warranty | 0 warranty not published, scored as none |
Specifications
| Aquasana HealthShield RO | Frizzlife PD800-TAM4 | |
|---|---|---|
| Filtration | ||
| Output | 800 gallons a day | 800 gallons a day |
| Pure to drain | 1.8:1 | 2:1 |
| Stages | 2 | 9 |
| Remineralization | No | Yes |
| NSF/ANSI 58 | Yes | No |
| Other certifications | NSF/ANSI 42, 53, 372, 401 | NSF/ANSI 372 |
| Replacement filters | $350 a year | $119 a year |
| Build | ||
| Tank | Tankless | Tankless |
| Booster pump | - | Yes |
| Smart faucet | No | Yes |
| Warranty | 2 years | - |