An apparatus for use in water purification including a cylindrical vessel comprising, within the cylindrical vessel, a first set of hydrocyclones, at least one intermediate set of hydrocyclones, and a final set of hydrocyclones, the sets of hydrocyclones arranged in series. In one embodiment, the hydrocyclones within each set of hydrocyclones are arranged in a parallel configuration, wherein each set of hydrocyclones is defined by a divider which causes the hydrocyclones in each set to operate in parallel. In one embodiment each hydrocyclone has a tangential inlet disposed within an inlet chamber of the cylindrical vessel and in fluid communication with an inlet connected to the inlet chamber, an overflow disposed within an overflow chamber of the cylindrical vessel, and an underflow disposed within an underflow chamber of the cylindrical vessel. In one embodiment, the cylindrical vessel comprises a first set of hydrocyclones and a second, final set of hydrocyclones.