**Abstract**

Haitian cities are more and more prone to demographic growth, which has a lasting effect on water distribution infrastructures, as well as those that make it possible to clean it up. They are in touch with the growing demand for water, but also with the management methods of this resource. Over the past 25 years, the enlarged agglomeration of Port-au-Prince, the largest agglomeration in the country, has experienced very strong urban expansion with the creation of new precarious spaces. The literature reports that Haiti is now more than 64% urban and 35% of its population lives in the metropolitan area of Port-au-Prince, in the West Department. Over the past decade, the footprint of the Port-au-Prince metropolitan area has grown by 35%. Recent observations on the formation and development of some slums highlight the country's vulnerability to land-based hazards, which support this form of urbanization through the emergence of environmental displaced persons. Canaan, a human settlement created following the earthquake of January 12, 2010 by presidential decree, and inhabited by the victims of this event, has a deficit in infrastructure and basic urban services. The results of our previous work on this territory lead to a much more in-depth reflection on the need to develop an index of vulnerability to environmental diseases for the population. In fact, most of the households that live there face very precarious situations. The health conditions associated with this context expose the population to increased risks of disease. The measures taken by families to treat water at home do not seem to limit their vulnerability to environmental diseases (infectious and chronic). Improving living conditions in Canaan with a view to sustainability therefore underlies major challenges. What avenues of intervention should be favored to facilitate a favorable development of the population, while taking into account the strong constraints that weigh on their daily lives? The objective of this study is precisely to analyze the vulnerability of the population to water-borne diseases.

**Keywords:** slums, vulnerability index, urban precariousness, water and sanitation quality, overpopulation, Canaan
