Abstract <p>Wastewater treatment plants (WWTPs) are essential infrastructures to protect environmental sustainability, human health, and urban resilience. Nevertheless, the task of finding the best locations to place WWTPs is still a daunting one because of the multi-dimensional, contradictory, and interdependent nature of the environmental, social and economic factors, in addition to the uncertainty and heterogeneity associated with multi-expert evaluations. Traditional multi-criteria decision-making (MCDM) models are frequently insufficient, since they do not all jointly (i) capture complex interdependence among parameters, (ii) ambiguity in expert judgments, and (iii) require transparent and strong prioritization of candidate locations. To address such constraints, this paper suggests a Cubic Multi-Fuzzy Hypersoft Set (CMFHSS)-based decision model that combines entropy-based objective weighting, a tailor-made Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and the Hybrid Weighted Arithmetic and Geometric Aggregation (HWAGA) operator. This allows it to be rigorously modeled when dealing with uncertainty, subtly model the use of multi-source expert opinion and hierarchies of criteria. The fact that a real-world case study of a sustainable WWTP site selection shows that the proposed framework is applicable in practice supports its stability, consistency, and superiority, sensitivity and comparative analysis with the traditional fuzzy and hypersoft models confirm the usefulness of the proposed framework. The findings demonstrate that CMFHSS-HWAGA-TOPSIS framework does not only provide more robust, interpretable, and flexible solutions but also serves the actual development of the United Nations sustainable development goals (SDGs) associated with clean water, sanitation, and sustainable cities development.</p> Graphical abstract <p></p>