This study aims to assess the quality of groundwater in the aquifer system of the Kandi Sedimentary Basin (BSK). The methodological approach adopted is based on the evaluation by the dosage of physico-chemical parameters of groundwater and the calculation of water quality indices (IQE). The results obtained show that the values ​​of electrical conductivity, pH, dissolved solids rate (06ppm and 584 ppm) and temperature (29_32.8 C) are within the quality standards with the exception of EPP samples LOLO and Drogine. The quality of groundwater in a (BSK) is assessed from different criteria. The calculation of water quality indices made it possible to identify the classes of groundwater quality and the different possible uses. Overall, the waters are of good quality and can be used for drinking, irrigation and industry.

Benin's renewable water resource potential is no less important. In the basement regions such as the Collines department, the hydrogeological characteristics made of crystalline rocks condition the recharge of the aquifers and therefore the durability of the boreholes drilled. The objective of this study is to determine the potential groundwater recharge zones at the scale of collines aquifer systems. Thus from planimetric data made of geological, pedological, hydrographic, slope, land use maps; satellite images and technical data from 50 boreholes, piezometric level mapping methods associated with multi-criteria analysis methods were applied. It appears from the results obtained that the aquifer system of the Hills located in a hydrogeologically difficult zone is made of a strong potential of recharge. The piezometric levels vary between around 40 m and 320 m. The highest are located in the north (recharge zone) of the department and gradually decrease towards the south to minimum values ​​of 40 m. The general trend of the flow is from North to South with domes and depressions. The main domes are in the north in the municipalities of Bantè and Ouessè. Depressions are observed south of the communes of Savalou and Dassa-Zoumè. The domes constitute the groundwater recharge zones while the depressions are the discharge zones. Recharge areas require protective measures to avoid pollution in the aquifer system.