NSF 42 vs NSF 53 -- what the certifications mean
NSF 42 certifies aesthetic improvement -- taste and odor (chlorine reduction). All basic carbon filters achieve NSF 42. NSF 53 certifies reduction of health-related contaminants: lead, cysts, VOCs, PFOA/PFOS. If your water concern is lead or PFOA/PFOS contamination, the filter must be NSF 53 certified. The Aquasana Claryum Direct Connect is NSF 42 and 53 certified -- valid for both taste and heavy metal concerns.
Claryum vs RO for Aquasana
Aquasana Claryum: removes 77 contaminants including lead and PFOA/PFOS, does not remove TDS or fluoride, no waste water, standard faucet pressure. Aquasana AQ-RO-3 RO: removes TDS, fluoride, nitrates in addition to Claryum's contaminants, produces waste water, lower flow rate, higher filter cost. Choose Claryum unless fluoride or nitrate removal is specifically needed.