Abstract
The study aimed to estimate direct and indirect costs of environmental degradation resulting from not fully reusing treated wastewater. To achieve our objectives, the study relied on probability distributions and economics equations. The study found that the percentage of treated wastewater reused ranged within 0.9%-47.3% at a 95% confidence level and, correspondingly, the amount of unused wastewater ranged within 52.7%-99.1% at a 95% confidence level. The total costs borne by the Saudi economy for treating wastewater were 658.67 million dollars in 2019. Direct costs of environmental degradation account for 75.5% of that total, whereas indirect costs account for the remaining 24.5% of the cost of environmental degradation of 658.67 million dollars in 2019. To reduce such costs, results of this study suggest the need to continue to assess and monitor the quality of treated wastewater and make full use of it for agricultural and industrial purposes.