Subject to sections
300g–4 and
300g–5 of this title, national primary drinking water regulations under this part shall apply to each public water system in each State; except that such regulations shall not apply to a public water system—
(1)which consists only of distribution and storage facilities (and does not have any collection and treatment facilities);
(2)which obtains all of its water from, but is not owned or operated by, a public water system to which such regulations apply;
(3)which does not sell water to any person; and
(4)which is not a carrier which conveys passengers in interstate commerce.