Background and objectives: The Physical, chemical and biological parameters one of the most important factors determining the quality of drinking water. The overall purpose of this project is to investigate how the quality of water entering the plant in changing the water-color and creating the foams in different units of water purification. 
Methods: This study is a case study and in real scale on the raw water inlet to the Koohsabz drinking water treatment plant has been done. The study was conducted over a period of 6 months (February 2016 to July 2017). In the first stage, the raw water quality was assessed according to standard methods. In the second step, the effect of each of the parameters on the color and foam formation in the water treatment process units and the mechanism of effects have been examined.
Results: Average changes in temperature, turbidity, the color of the water entering the plant during the study period were 15.8oC, 6NTU, and 6TCU respectively and pH ranges from 6.9 to 8.4. Mean change of EC, TOC and DOC respectively is; 765 μS / cm, 5.8mg /l and 3.53mg /l. The average change UV254 and SUVA were 0.178 l / m and 5.856 L/ mg, respectively. Also, the mean changes of humic acid, surfactant, and chlorophyll a in the input raw water were 0.24, 0.05 mg / l and 2.4 μg/m2, respectively.
Conclusion: Investigations showed that the water quality parameters of water entering the treatment plant are effective in creating color and foam in water treatment process units.