In 2021 the lack of safe water for the human being needs is still an issue, especially in the developing countries. To overcome this problem, the United Nations establish the SDG 6 “Ensure availability and sustainable management of water and sanitation for all” with the purpose to give safe water to all the people in need within 2030. The present work follows the purpose of the Goal 6 and it focuses on the case study of the Nosy Mitsio island in the North of Madagascar. In the island the local population suffers the absence of a water supply system for irrigation of vegetable gardens: for now, the locals practice a subsistence farming, changing the location of the vegetable gardens when the soil loses its fertility and stopping the farm during the dry season.