In many developing countries including Nepal, water fetching is traditionally conducted by women and girls. In a mountainous hinterland of Nepal without systematic water and electricity supply, it is inevitably laborious, and as a result, girls receive fewer educational opportunities than boys. This paper aims to identify the causal effect of household water accessibility on children’s educational attainment measured by school attendance, grade repetition, and completion of primary and lower secondary schools in remote mountainous villages in Nepal. The estimation results evince that water hauling hinders girls from completing schooling, indicating that a one-hour increase in the time spent going to and from the water source will decrease the probability of female children completing primary school by 24.1 percentage points, while male children do not drop out, although they are more likely to repeat a grade. This implies that increased water accessibility—for example, by providing a solar water pumping system that the Nepali government promotes—improves household wellbeing, particularly girls’ educational attainment, by reducing the burden of water collection.