Improved water and sanitation in early life and cognition in adolescence: evidence from four countries^*

Abstract Early life environmental exposures, such as drinking water quality and sanitation, can have long lasting effects on human capital accumulation. Using matched samples of over 8000 children across Ethiopia, India, Peru, and Vietnam, this paper examines the relationship between early life access to improved drinking water and improved sanitation and cognition at the age of fifteen. It finds that children with early life access to improved drinking water score 1.6–2.8 percentage points higher on math, reading, and vocabulary tests. A similar, yet less precisely measured, pattern emerges for early life access to improved sanitation. Analysis by gender shows that the effects of early life drinking water access are stronger and more precise among girls. An examination of pathways underlying these relationships provides preliminary evidence that learning over the life course is a leading mechanism. Quantifying these long-term cognitive benefits provides insight for directing and prioritizing resources for global efforts to increase equitable access to improved drinking water and sanitation.