Qualitative Assessment of Rain Water Harvested from Roof Top Catchments: Case Study of Embakasi, Nairobi County
Joanne N. Gakungu
Joanne N. Gakungu, Department of SMARTEC, Sustainable Materials Research & Technology Centre, JKUAT.
Manuscript received on August 08, 2013. | Revised Manuscript received on August 29, 2013. | Manuscript published on September 05, 2013. | PP: 263-266 | Volume-3, Issue-4, September 2013. | Retrieval Number: D1834093413/2013©BEIESP
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: Rain Water Harvesting (RWH), in its broadest sense, is a technology used for collecting and storing rainwater for human use from rooftops, land surfaces or rock catchments using simple techniques such as jars and pots as well as engineered techniques . This paper aims to assess the quality of harvested roof-top rainwater from three different roofing materials in Embakasi area in Nairobi County. The roofing materials are corrugated iron sheets, clay tiles and concrete tiles. Chemical analysis included testing for iron, copper, zinc, fluoride, aluminium, lead, zinc, manganese, sodium and potassium. Physical analysis of pH and turbidity was carried out as well as bacteriological analysis for Escherichia coli (E. Coli) and total coliform. All the rainwater samples results for the samples taken after first run-off, were within the guidelines for both chemical and microbiological parameters established by the World Health Organization . On the contrary, turbidity levels were higher than the maximum allowable concentration for drinking purposes hence the need to allow the first run –off during any rainfall event. As revealed from the analysis, all the samples require some level of treatment e.g. chlorination in order to ensure they meet regulatory standards for drinking water. However all water samples are quite safe for all other domestic uses including laundry, toilet flushing, bathing and other general cleaning. The integrated management must consist of regular cleaning of the catchment areas and the storage tanks and the employment of automated mechanical systems for discarding the first portion of each rainfall. The use of clay roofing tiles is preferable but due to cost, corrugated iron sheets maybe adopted.
Keywords: Rain Water Harvesting, Roofing Materials, Water Quality.