In Dakar capital city of Senegal, the urban agriculture is in high expansion. Since the progressive increase of salinity in the local groundwater (Céanes water), raw wastewater is used to water the crops. The objective of this study is to assess chemical and microbiological quality of the groundwater underlying the irrigated plots and to identify the sources of pollution. This work was carried out in the sites of Pikine and Patte d’Oie in Dakar Senegal. Chemical analysis of irrigation water showed that in Pikine, the conductivity of Céanes water was higher (4822±2411 μS cm-1) than those of the wastewater (3579±1242 μS cm-1 ; p<0.04), while at Patte d’Oie it was less salted (<3000 μS cm-1). The quantity of total nitrogen of irrigation water in both sites was higher than the WHO’s threshold (5-30 mg l-1). Salmonella spp. was isolated in 35 % of the irrigation water. One wastewater sample was Vibrio cholerae positive. The impact of irrigation water on the chemical and microbiological quality of the groundwater is strongly influenced by precipitations and is different according to the site considered. This work showed that the use of polluted water and organic manures can spoil the quality of the groundwater and constitute a health threat. Urban agriculture