Aquasana OptimH2O Reverse Osmosis + Claryum Under Counter Water Filter System

#3 of 8 under sink water filters tested

No sponsored placements·By Renée Torres

9.0R3 Score / 10

RecommendedWe'd buy this without hesitation.

No sponsored placements· By Renée Torres

The bottom line

What the product listing won't tell you

Know before you buy

The OptimH2O's Exceptional rating comes from its certification depth, not its maintenance convenience. NSF P473 — the PFAS-specific standard — plus four other NSF certifications is the broadest certified coverage in this category. The honest tradeoff is the pre-filter: 365 gallons means roughly twice-yearly replacements at roughly $211 per year. That's the real cost of this system's certification breadth. If that schedule fits your routine, the safety credentials are the strongest available in a DIY under-sink format.

Buy it if

You need NSF P473 — the PFAS-specific certification — combined with NSF 53 lead coverage, NSF 401 emerging contaminants, and NSF 58 comprehensive RO in a single under-sink system.
You want full test transparency: Aquasana's certified products page lets you verify every contaminant claim before you buy.
You're comfortable with semi-annual filter replacements and building that maintenance habit in exchange for the deepest certification profile in the category.
Your household water has documented PFAS, lead, chloramine, or emerging contaminant concerns that require formal NSF certification to address.

Skip if

Frequent filter changes feel unmanageable — at standard household usage the pre-filter needs replacing every 6 months.
You're optimizing for low annual running cost — roughly $211 per year in filter replacements is above average for an under-sink system.
You want a simple install without drilling a new hole — the dedicated faucet requires a new hole in your sink deck or counter.