A. O. Smith RO with Microbial Boost AO-US-RO-MB-4000 vs iSpring RCC7AK

Only the A. O. Smith RO with Microbial Boost AO-US-RO-MB-4000 is certified to reduce PFAS, lead, chlorine and chloramine and 7 more. Verdict: the A. O. Smith RO with Microbial Boost AO-US-RO-MB-4000 for broader certified protection (12 vs 1 of the contaminants we track); the iSpring RCC7AK if running cost matters more. Replacement filters and water for 2 people cost about $270 a year on the A. O. Smith RO with Microbial Boost AO-US-RO-MB-4000 and $242 on the iSpring RCC7AK; they cost — and $240 to buy.