§ 141.400 General requirements and applicability.

(a) Scope of this subpart. The requirements of this subpart S constitute National Primary Drinking Water Regulations.

(b) Applicability. This subpart applies to all public water systems that use ground water except that it does not apply to public water systems that combine all of their ground water with surface water or with ground water under the direct influence of surface water prior to treatment under subpart H. For the purposes of this subpart, “ground water system” is defined as any public water system meeting this applicability statement, including consecutive systems receiving finished ground water.