Water, the most common and vital solvent for wet processes, such as dyeing, printing, rinsing, sizing, desizing, finishing, bleaching and many other purposes, has a great influence over textile processes. This project work was intended to investigate the parameters of various fastness properties at different quality of water hardness in the application of hot brand reactive dyes. influence of water quality on dyeing of cotton knit fabric with hot brand reactive dye. The effects of various fastness (color fastness to wash, pilling test, rubbing test and perspiration test) properties of dyes were also studied and reported in this study in details. Single color (Red) is used for the shade of 3% and varied water hardness of 13.5 PPM, 174 PPM, 114 PPM, 54 PPM and 246 PPM respectively. It is visualized that different grades of water hardness showed in different fastness and different depth of red hue for using reactive dyes having shade of 3%.