[Pollution of the groundwater in the city of Niamey, Niger].

We conducted a study on chemical and bacteriological groundwater pollution in Niamey, a Sahelian city of some 700,000 inhabitants. A total of 22 wells and 24 bore-holes were selected on a geological and socio-economic basis. The superficial aquifers, located on each bank of the River Niger and connected to the wells, presented high levels of oxidizable nitrogen and bacteriological pollution (coliform and faecal Streptococcus) which make the water unfit for human consumption. The deep aquifer, which supplies pumps, was also polluted but to a lesser degree. Faecal pollution increased after the rainy season. The lack of sanitation in Niamey and the seepage of polluted matters from the superficial layers could explain this pollution. Eventually, the use of the groundwater could increase and constitute a major health risk for the majority of the inhabitants of Niamey.