Improving the conditions of water supply is an economic development factor of great consideration in poor countries. The wind power devices described in this article have been designed to give satisfaction in specific material conditions, notably those in Madagascar. By using low technical methods and in respecting the environment, these devices serve as the catalyst for immediate and long-term economic development. Three different versions of the device, corresponding to domestic, agricultural and light equipment needs, respectively, are worked out using a rational method of dimensioning.