Section 142.304 - For which of the regulatory requirements is a small system variance available?(a) A small system variance is not available under this subpart for a national primary drinking water regulation for a microbial contaminant (including a bacterium, virus, or other organism) or an indicator or treatment technique for a microbial contaminant.(b) A small system variance under this subpart is otherwise only available for compliance with a requirement specifying a maximum contaminant level or treatment technique for a contaminant with respect to which; (1) a national primary drinking water regulation was promulgated on or after January 1, 1986; and(2) the Administrator has published a small system variance technology pursuant to Section 1412(b)(15) of the Act. Note to paragraph (b)(1): Small system variances are not available for public water systems above the pre-1986 maximum contaminant level even if subsequently revised. If the Agency revises a pre-1986 maximum contaminant level and makes it more stringent, then a variance would be available for that contaminant, but only up to the pre-1986 maximum contaminant level.