Tube settlers are gravity settlers wherein the settler is provided with No. of inclined tubes to increase the surface area of separation of solids from the liquid.The basic theory of tube settlers is that it reduces the detention period to few minutes and achieves the required settling of the turbidity in comparison with conventional settling basin having detention period of 1-4 hrs. This is possible because of the vast area for settlement offered by the tubes installed within the clarifier unit. The area of settling basin is reduced with the high over flow rates viz. to the extent of two to three times higher than convention basins.