40 CFR 142.3 - Scope.
(a) Except where otherwise provided, this part applies to each public water system in each State; except that this part shall not apply to a public water system which meets all of the following conditions:
(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.
(b) In order to qualify for primary enforcement responsibility, a State's program for enforcement of primary drinking water regulations must apply to all other public water systems in the State, except for:
(1) Public water systems on carriers which convey passengers in interstate commerce;
(2) Public water systems on Indian land with respect to which the State does not have the necessary jurisdiction or its jurisdiction is in question; or
(c) Section 1451 of the SDWA authorizes the Administrator to delegate primary enforcement responsibility for public water systems to Indian Tribes. An Indian Tribe must meet the statutory criteria at 42 U.S.C. 300j-11(b)(1) before it is eligible to apply for Public Water System Supervision grants and primary enforcement responsibility. All primary enforcement responsibility requirements of parts 141 and 142 apply to Indian Tribes except where specifically noted.