The Global Burden of Disease is the official metrics of World Health Organization in use to support public health evidence-based decision-making. It has been systematically used to assess environmental risk factors such as unsafe Water, Sanitation and Hygiene (WASH), as part of the measurement of Environmental Burden (EB). This article reports on the first study in Brazil that estimates the EB attributable to unsafe WASH associated with diarrhea for children under five years old for the country and macro-regions for 1998. The EB of diarrhea for this subgroup was estimated using the population attributable fraction (PAF) method for four scenarios of exposition to unsafe WASH. Results of PAF were multiplied by the EB obtained from the 1998 Brazilian GDB Study. The regions with higher EB for children below five years old were north and northeast, both predominantly rural. The EB attributable to unsafe WASH was 15% in 1998. The estimation of the EB of diarrhea contributes to the re-assessment of Brazil's attainment of the Millennium Development Goals (MDG) in both health and environmental dimensions. Results obtained indicated that the country's precarious conditions of WASH in rural areas are below the goals of MDG, as well as in impoverished urban areas.