A. O. Smith AO-US-200 2-Stage Under Sink vs Waterdrop 10UA

Only the A. O. Smith AO-US-200 2-Stage Under Sink is certified to reduce PFAS, lead, chloramine and mercury and 3 more. Verdict: the A. O. Smith AO-US-200 2-Stage Under Sink for broader certified protection (8 vs 1 of the contaminants we track); the Waterdrop 10UA if running cost matters more. Replacement filters and water for 2 people cost about $168 a year on the A. O. Smith AO-US-200 2-Stage Under Sink and $31 on the Waterdrop 10UA; they cost $140 and $59 to buy.