Climate change is severely affecting the availability of water and its quality. 1 Therefore it represents a direct challenge to health. Not only the water-born, but also the vector and temperature-related diseases are challenging the existing health system and safe water supply. Thus, water and health security have progressively been challenged primarily by pollution, waste, toxins and climate-change-related hazards and disasters.This chapter links the changing understanding on socio-environmental deterioration with water and health security. Using a case study of Mexico, it reviews the effects on the environment and the human well-being of the dominant economic model based on wasteful fossil energy, social inequality, consumerism, fashion, and growth concentrated in small elites. This model has brought both the planet and society as a whole to its limits of survival, but it has also affected regions, cultures and social classes differently. Poor countries and vulnerable groups have become the main victims suffering from socio-economic and climate-induced changes. In Mexico, the epidemiology has been changing, and traditional illnesses (diarrhoea, pulmonary conditions, under-nourishment) coexist with modern ones linked to the transformation of the diet (diabetes, obesity, cardiovascular diseases, cancer) and the pollution of water, air and soil (intoxication, respiratory, kidney and skin problems).At the conceptual level, in the framework of the PEISOR model this chapter explores the complex interaction between anthropogenic drivers, impacts of and policy responses to climate change, their interrelationship with the dominant 1 This text was adapted from two former published chapters by Oswald Spring, Úrsula (2012).