The purpose of this Directive is to prevent the pollution of groundwater by substances belonging to the families and groups of substances in lists I or II in the Annex, and as far as possible to check or eliminate the consequences of pollution which has already occurred. Member States shall prohibit all direct discharge of substances in list I, that shall be subject to prior investigation of these substances which might lead to indirect discharge. In the light of that investigation, Member States shall prohibit such activity or shall grant authorization provided that all the technical precautions necessary to prevent such discharge are observed, and shall take all appropriate measures to prevent any indirect discharge of substances in list I due to activities on or in the ground. They shall notify such measures to the Commission, which, in the light of this information, may submit proposals to the Council for revision of this Directive.