Quantitative and Qualitative Assessment of Air-Conditioner Condensate as a Supplementary Urban Water Resource

This study demonstrates that condensate generated by air-conditioning systems in administrative buildings in Saveh, Iran, represents a potentially valuable supplementary water resource in arid urban environments. The mean daily condensate production was 322.5 mL per unit, with cooling capacity and ambient temperature identified as the principal determinants of yield (R² = 0.89), indicating a strong positive correlation. Physicochemical characterization revealed that the condensate was characterized by very low total dissolved solids, negligible hardness, and minimal nutrient concentrations. However, approximately 50% of the samples exhibited acidic pH values, suggesting the need for pH stabilization prior to reuse. Microbiological analysis detected the presence of coliform bacteria and elevated heterotrophic plate counts in 40% of the samples, thereby precluding direct potable application without appropriate treatment. Despite these limitations, the results indicate that relatively simple treatment measures, including pH adjustment, filtration, and disinfection, could render air-conditioning condensate suitable for non-potable applications. Accordingly, integrating condensate recovery into building-scale water reuse frameworks may enhance urban water circularity and strengthen the resilience of water resource management systems in regions experiencing chronic water scarcity. • Air-conditioner condensate exhibited excellent physicochemical quality, characterized by very low total dissolved solids (76 mg/L), zero hardness, and negligible salinity. • Condensate production was strongly influenced by climatic factors, with temperature difference and maximum temperature accounting for up to 89% of the observed variability (R² = 0.89). • Approximately half of the samples had acidic pH, and 40% showed microbial contamination, highlighting the need for minimal treatment before reuse. • After simple pH adjustment, filtration, and disinfection, AC condensate can provide a reliable non-potable water source in water-scarce urban environments.