Despite an average annual accumulation of 1850 mm, the high variability of rainfall, the distribution of the population and activities but also the numerous constraints subject New Caledonia to recurring imbalances between resources and uses. Surface water is naturally more vulnerable, although its use is largely predominant in New Caledonia. They often appear critical, while the qualitative and quantitative challenges of groundwater make them strategic resources with potential that remains largely to be clarified and developed. This chapter describes and analyzes the numerous existing constraints and presents issues concerning water resources.