El-Oued is known for some diseases caused by fluoride concentration in drinkable water. To reduce it, we have chosen a sample with the highest content of fluoride among many sources in order to coagulate it with Al 2 (SO 4 ) 3 ·18H 2 O, Fe 2 (SO 4 ) 3 ·H 2 O and FeSO 4 . In order to get better reduction yield of fluoride, a study has been done on the influencing parameters (concentration, pH, temperature) to choose the best conditions. The remove of fluoride is favorable at low concentration of Al 2 (SO 4 ) 3 , at room temperature and normal acidity.