Recycling of wastewater is an important issue as it is used for many important applications such as industries, agriculture, household applications and due to water scarcity across the different countries. Wastewater treatment is an important activity as it protects human being and the ecosystem from harmful and toxic elements present in wastewater. Performance evaluation of wastewater treatment technologies being complex Multi-criteria Decision Making (MCDM) problem that has contradictory evaluation factors. This paper is focused on the analysis of factors that affect evaluation of wastewater treatment technologies and their impact by developing a model which combine Analytical Hierarchy Process (AHP) and Grey Relational Analysis (GRA) for the assessment and ranking wastewater treatment technologies (WWTTs) respectively. The best WWTT is chosen based on data acquired through a case study. AHP is applied for computing criteria weights based on comparative significance while Grey Relational Analysis method is applied for ranking and selecting the wastewater treatment technologies. Sensitivity analysis is performed to show the impact of grey relational scores of alternatives in line with variations of distinguished coefficients.