The inner-recycling continuous sand filter is a new water treatment system that uses micro-flocculation theory for better filtration. The key design parameters for optimal performance are: filter material diameter of 0.7 to 1.0 mm, filter bed depth of 0.6 m, filtration velocity less than 12 m/h, gas to water ratio of 9:11, and sand recycling rate of 2 to 4 mm/min.