<p>The Kebili oasis, located in southern Tunisia, is currently suffering from a serious salinisation problem affecting wells that draw from the Complex Terminal shallow groundwater aquifer. For this reason, an investigation study was carried out, including interviews with 68 well owners, as well as an analysis of historical drilling and logging data, and a campaign of 51 water samples was conducted for physicochemical and major ions analyses. The aim of this study was twofold: firstly, to characterise the extent and evolution of groundwater salinisation in the Kebili region for CT and CI wells; and secondly, to identify the causes. The results show that integrity problems in deep Continental Intercalaire (CI) wells are responsible for widespread Complex Terminal (CT) groundwater salinisation. Indeed, six deep wells (DW-1, 16, 35, 42, 43, 58) have shown an integrity issue responsible for a sudden and significant increase in the total dissolved salts, reaching a maximum concentration of 169.7&#xa0;g/l. Four deep wells have already affected nearby shallow wells. This has led to increases in salinity and sometimes temperature, including 36 shallow water wells. In these wells, salinity has locally reached 25.1&#xa0;g/l. Workovers carried out on some deep wells have resulted in significant improvements in water quality, but have not restored the original quality. In conclusion, an ongoing ecological disaster has been identified in the Kebili region, which is threatening the Complex Terminal groundwater resource on a regional scale. In order to regain control of this issue, urgent inspections and proactive measures should be implemented in all deep wells to prevent the serious consequences of integrity loss. Furthermore, it is recommended that a well integrity investigation be conducted. This will highlight the weaknesses in the current well design and improve it in the future.</p>