An experimental model for the multiple stage filtration (MSF) process has been designed which
consists of Roughing Filter (RF) and Slow Sand Filter (SSF) and located at Giza Water Treatment
plant. The results indicated the purification of water with levels of contamination well above those
treated by SSF alone, and high efficiency in turbidity removal (90-99%). The overall efficiency is
increased by reducing filter media size or rate of filtration. Turbidity removal contribution of RF to
overall removal is around 77% and around 19% for SSF. MSF can handle turbidity level up to 30 NTU
and give effluent turbidity less than 0.5 NTU. At rate of filtration higher than 0.25 m/hr, removal of
turbidity deceases significantly. The SSF should be cleaned every two months to maintain a maximum
head loss of 63cm.