Climate change is expected to increase floods, extreme precipitation events, droughts, air and water temperatures, and sea levels in coastal areas. All of these meteorological and climatic phenomena are likely to affect the safety of drinking water supplies. This chapter presents case studies of how the interactions of waterborne bacteria, protozoa, viruses, harmful algal blooms, and chemicals with environmental and climatic conditions have contributed to outbreaks of human disease. Through these case studies, we note that infants, young children, and young mothers have been particularly vulnerable to outbreaks of waterborne disease linked to climate change, as well as coastal and island populations.