ABSTRACT This paper proposes a method for prioritizing sewer cleaning operations in the absence of historical data on failures. The method utilizes the Induced Ordered Weighted Averaging (IOWA) multi-criteria decision-making technique, incorporating experts' opinions to regulate subjective inferences and ascertain uncertainty. The study considers ten parameters categorized into three main focuses: structural, environmental, and operational to analyze sewer pipe conditions. As a case study, four small zones in Tehran city were prioritized using the proposed methodology. The findings reveal that (1) decision-makers' subjective priorities and evaluations do not significantly influence critical cleaning options, (2) pipe diameter is the most effective parameter for prioritizing since it allows pipes to be meaningfully categorized and compared, and (3) slope, age, depth, upstream manhole condition, and the number of connections and laterals are more important than other parameters. Overall, this study provides valuable insights into developing effective prioritization strategies for sewer cleaning operations.