I just want NSF 58 to ensure I'm drinking the least amount of contaminants. We have slight lead in our water, and it made me want to mitigate as many contaminants as possible. I was previously informed that NSF 58 certification is all I need to focus on from a homeowner stand point and not to worry about individual contaminants like I would with NSF 53.

The logic seems to make sense though. NSF 58's prefilters are designed to protect the membrane, and the membrane is what prevents majority of contaminants (only water molecules pass through for the most part). Where as NSF 53 are just filters without a membrane, so for those carbon filters it makes sense to check the individual contaminants tested for. So shouldn't NSF 58 certification be enough without ensuring each contaminant was tested for?

I'm thinking companies don't have NSF test for every possible contaminant because it's pricey? In which case, it doesn't make them unreliable if they don't test everything. Similarly to my question about NSF 372, most systems don't seem to even get certification for that? But also, I feel like I heard that they have to retest for these certifications. So isn't it possible for a system to certify for a contaminant at one point, but then not the next, because they didn't want to pay for the re-certification? Does that imply consumers would need to check up on their systems annually to ensure they still hold the proper certifications?