Color of wastewater is one of the indicators that states the quality of wastewater from industry sector flow into public water resources. It is very difficult to decide that the color of wastewater can be accepted or cannot. The conflict between the public sector and industrial sector may occurs. This research is interested in developing the practicable and sicentific method for wastewater color evaluation which leads to an answer that can be accepted or not accepted. The Munsell Color System was applied to color measurement in this research. The system uses “hue”, “value”, and “choma” as the parameters of color. To Query the public opinion towards the threshold limit of acceptable colors was done. The wastewater from a dye factory in Samuthprakarn province of Thailand flow into public water resource was a case study. The result from 70% of population opinions stated that the threshold limit of color can be represents by “hue”, “value” and “choma”. At the same time the laboratory parameter such as COD can able to predict color of wastewater (R2 = 0.80). The key point in the development of the evaluation is to improve the reliable of public opinions by color parameters and to support the opinions by conventional laboratory parameters