Among the European Union Directives enacted on water management and environmental protection, Directive 98/83/EC defines the mandatory quality standards for water intended for human consumption in order to protect human health. The implementation of this Directive has often encountered delays due to the following: the exact mechanisms for monitoring and enforcement have not yet been fully identified, several EU countries had set more stringent drinking water standards while others needed to update their national regulation, financial resources to comply with the directive were not always available, and the recent enlargement of the EU has raised further issues. In this study an evaluation of the regulations on drinking water in European and Mediterranean.countries was carried out. The attention focused on Directive 98/83/EC and to its implementation in the Member States, also considering the recent (2004) EU enlargement, which brought ten new countries into the European Union. Finally, a comparison among the new standards on disinfection by-products (DBPs) adopted by the different countries is presented along with the USEPA approach to DBPs control.