Increasing the needs to drinking, purified water impose constructing new water treatment plants, which needs big expenditures due to the operation and maintenance and consumable material costs such as Alum Sulphate used in the settling activities in addition to the costs of operation and maintenance of settlers. The using of hydrocylone as a pre-filtering system has been studied in this paper. Series of tests (runs) has been carried out on a designated hydrocylone with diameter of 85mm and total length of 510mm which is convenience to a pumping rate of 50 L/min and pressure of 150,000 Pascal. To investigate the results, a mobile turbidity meter has been used to measure the turbidity and Bettersize particles size analyzer has been used to investigate particles distribution which caused each turbidity for both inlet feed water and overflow water. For all runs, the hydrocylone results showed that the used hydrocylone recovered 84.6% of the feed water through the overflow outlet and recovered 15.4% through the underflow outlet, it is started with a feed water turbidity of 300NTU, and the hydrocylone concentrated the solids loaded in the raw water by 155.66% and reduced the turbidity by 52.33%. The results of the present work indicated that the usage of hydrocyclone can efficiently reduce the solid loading of raw water pumped into a water treatment facility, the grade removal efficiency are affected by the phenomena of collision and agglomeration of particles inside the hydrocyclone which will change the size distribution of a specific grades. The x50 of in the experiment was (37μm) and the hydrocyclone succeed in removing

42.6% of the suspended solids fed with the inlet feed. And it removed 47.3% of the settable solids. It is also clear that the hydrocyclone succeed in lowering the mean diameter of solids in the overflow to 35.41 μm from 75.11 μm, ie the hydrocyclone succeed to reduce the mean by 53.25%.