Urban Water Disinfection and Mortality Decline in Developing Countries

Historically, improvements in municipal water quality reduced mortality substantially in wealthy countries. However, water disinfection has not produced equivalent benefits in developing countries today. We investigate this puzzle by analyzing a large-scale municipal water disinfection program in Mexico that increased water chlorination coverage from 55% to 90% within 18 months. On average, the program reduced childhood diarrheal disease mortality rates by 50%. However, age (degradation) of water pipes and inadequate sanitation infrastructure attenuated these benefits substantially, ranging from no decline in cities with the worst infrastructure to 80% in those with the best – a decline consistent with historical experience.