wcm.01.2026.60.65

Drainage canals in Kurunegala city in Sri Lanka are facing eutrophication and lousy odor even though wastewater is treated in the sewage treatment plant (STP). Wastewater from the city is effectively treated to acceptable quality complying with discharge standards and released back to the same drains. This study investigated the recontamination of treated water in urban drains and explored the potential of utilizing treated water for direct non-potable uses (NPU) to achieve multiple Sustainable Development Goals (SDGs). Water samples from five sampling sites downstream to the STP were taken and temporal and spatial variations of physicochemical parameters and E. coli were assessed. It was observed that the water quality in urban drains is a result of excessive nutrients in the water, likely caused by recontamination of the treated wastewater by external sources. After the establishment of the STP, current water quality in the canals depicted only marginal improvement (p<0.05, GLM) except for TDS, pH, conductivity, and E. coli. To address this issue, the best solution could be employed is to direct treated wastewater for NPUs such as agricultural irrigation, industrial processes, and urban landscaping, by which recontamination of the treated wastewater in the drains could be minimized. Treated wastewater utilization in NPU will help to reach multiple SDGs, thus increasing social benefits for the local population. The results of this research indicate that using treated wastewater in urban areas is a viable method of fulfilling many of the SDG goals, especially those related to water scarcity. Importance of diverting treated wastewater away from polluted canals to meet increasing water needs is emphasized by the findings.