Alum was used as a defluoridating agent at the concentration of (25,50.100,500,1000 and 1500 mg per 100ml of fluoride rich water for the contact time of 6,12, 18 and  24 hours. Alum powder was used at the diameter of <0.3 mm, 0.6mm to 1.0mm and >l.0mm. Results showed that alum at the concentration of 25mg/100ml for the contact time of 18 hours, in the powder form reduced the fluoride to permissible limits of 1.5 ppm.