there are NSF/ANSI standards for water treatment: https://www.nsf.org/consumer-resources/articles/standards-water-treatment-systems https://www.nsf.org/consumer

there are NSF/ANSI standards for water treatment: https://www.nsf.org/consumer-resources/articles/standards-water-treatment-systems https://www.nsf.org/consumer-resources/articles/standards-wa... There are filters that are certified by NSF to comply with those standards https://info.nsf.org/certified/dwtu/ https://info.nsf.org/certified/dwtu/