Although it recognizes the tangible economic benefits to health and income that may derive from greater safety of supply and improved time savings in procurement, planning for improvements of urban water systems in developing countries has overlooked other ways in which water may influence health and income among the poor. In these populations the price of water may further affect health and labor productivity, both directly through its impact on nutrition and indirectly through its impact on housing size and quality and on residential density. What at first might seem a straightforward equity issue in planning may thus be an issue of economic efficiency as well. Failure to account for the fuller range of tangible benefits associated with improvements in water supply may lead to underestimation of returns to investment and therefore to economically inefficient investment. ¿ American Geophysical Union 1993