Unless specifically exempted by the provisions of Public Utilities Article, §5-204, Annotated Code of Maryland, a person shall apply to the Commission, before construction, for authority to construct a water system, sewage disposal system, or both, to be devoted to public use. Water company applicants claiming “not-for-gain” status shall submit full and complete documentation supporting this claim for review and determination by the Commission, as required by these regulations. Sewage disposal company applicants, whether “for-gain” or not, shall fully comply with all provisions of this subtitle, the law, and COMAR 20.75. Water company applicants shall fully comply with all provisions of this subtitle, the law, and COMAR 20.70.