The CONTRAFAST clarifier is a high rate sludge thickening softener. Utilizing a combination of internal and external sludge recirculation and tube settling clarification, the CONTRAFAST process is capable of running at rise rates of 6 gpm/sq.ft. and higher. This is over 4 times the rate typically used for onventional lime softening clarifiers. In addition, the CONTRAFAST unit produces sludge with more than 20% solids by weight, eliminating the need for a sludge thickener. Therefore the combination of the high rise rate, and the elimination of the separate thickener, reduces the total process footprint. The entire process takes place in a single vessel, greatly simplifying installation.