In this research work, a comparative analysis of the legal framework for water reuse in Brazil and Portugal within their scenarios of sanitation and water resources management is presented. It appears that the coverage in drinking water and sanitation services is quite different between the two countries. However, the respective rates of reuse of effluents in relation to the total wastewater treated are similar (1.5% in Brazil and 1.2% in Portugal). Water reuse has become an important alternative source of increasing water availability for sustainable development. Despite the legal aspects of both countries presenting similar management instruments, Brazil tends to be more flexible in relation to the standards of fecal contamination indicators for the reuse of water for irrigation of urban environments, firefighting, and street washing. In the case of reuse for irrigation of agricultural environments and flushing the toilet, legal standards are equally restrictive. Standards for use in civil construction and clearing wastewater galleries are only included in the Brazilian regulatory document.