Assessment of Rooftop Rainwater Harvesting Potential as an Alternative Water Source for the Commercial Buildings in Merkato, Addis Ababa
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Date
2026-06-01
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Addis Ababa University
Abstract
Rapid urbanization and increasing commercial activity in Addis Ababa have put high pressure on the already struggling urban water supply system of AAWSA. This challenge is particularly evident in Merkato, where commercial buildings experience frequent water shortages and supply interruptions. In this context, rooftop rainwater harvesting presents a promising supplementary water source. Therefore, this study assessed the potential of rooftop rainwater harvesting for commercial buildings in Merkato, Addis Ababa. Both qualitative and quantitative research approaches are employed. A census survey was conducted on 34 commercial buildings. The findings showed that municipal water remains the dominant source of supply. However, the AAWSA water supply is unreliable. All buildings use storage tank as coping mechanism for the shortage. The recorded municipal water consumption ranged from 65.28 m³/year to 8352.00 m³/year. Non potable activities represented the dominant category of water use. 79.4% of buildings used water primarily for activities such as toilet cleaning and floor cleaning. All surveyed buildings are physically suitable for RRWH with gutters and roof materials favorable for runoff collection. The estimated annual RRWH potential ranged from 192.64 m³/year to 3693.43 m³/year with a contribution to existing municipal water consumption varying from 6.07% to 169.20%. The analysis of monthly variation revealed that RRWH potential is highly seasonal, with the highest yields occurring during July and August, while minimal contributions are observed in December and January. The study concludes that RRWH has significant potential to reduce dependence on AAWSA and improve water security in commercial buildings in Merkato. Promoting its use, particularly for non-potable applications, can therefore contribute meaningfully to strengthening the urban water supply system.
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Rooftop rainwater harvesting, commercial buildings, Non-potable water use, Water supply, Merkato