Drinking water is a basic food and its access is one of the fundamental human needs. For Ouagadougou, it comes from the station of water treatment of surface at Paspanga and Ziga. The mud increase constitutes a persistent phenomenon in the treatments of water of Paspanga. The objective of this work was to find the causes of this phenomenon in order to optimize the costs and rate of drinking water production. To be done, the physicochemical parameters and the tests of rough water treatments were carried out according to standards of quality. The results showed that water is potabilisable. Indeed, the average of turbidity, content of organic matter and suspended matter of water were respectively 116,52 NTU, 10,85 mg/l, 4,72 mg/l of O2 in May and 719,13 NTU, 21,07 mg/l, 13,08 O2 mg/l from June to July. The pH of water varied to 6,89 in May; to 7.50 in June and July. In addition, the results showed that the gas production revealed is progressive over time, which would mean that the mud increased would be a result of two factors: the quality of raw water and the production of gas at the bottom of the decanters.

Decanter, rising mud, treatment