Coagulation and flocculation tests were carried out on water samples from Nairobi River using conventional jar test apparatus at room temperature. The pH of the water was varied using 1 M HCL and NaOH. River water 500 mL was transferred to 1 L jars and placed in the jar test apparatus. Banana pith coagulant was added at dosages of 0.1–1 kg/m3. The mixture was subjected to 3 min of rapid mixing at 180 rpm followed by 20 min of mixing at10 rpm and 30 min of settling. During settling, samples were withdrawn with pipette from 2 cm depth at 5 min intervals for 30 min.