Quality of Rainwater from Different Roof Material

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Author(s) Olaoye, R.A | Olaniyan,O.S
Pages 1413-1421
Volume 2
Issue 8
Date August, 2012
Keywords Rainwater,Contamination, Roof material, water quality, Asbestos

Abstract

Roof material is an important consideration when designing a rainwater catchment system .This is because it affects the quality of the harvested rainwater which invariably affects the usage as potable or non potable. This study was carried out to determine the quality of rainwater from four different roofing materials (asbestos, aluminium, concrete and corrugated plastic) within Ogbomosho North Local Government Area of Oyo State, Nigeria, between the months of July to October, 2011. The rainwater samples were taken to the laboratory and analyzed as recommended by Nigerian standard for Drinking Water Quality (NSDQW) and World Health Organization (WHO).

All the Physical and most of the chemical parameters analyzed conformed to the recommended standard value apart from chloride and total hardness value. Of interest is the rainwater sample from asbestos roofing sheet which had the highest mean value for pH (6.75), total hardness (84 – 86mg/l), aluminium concentration (3 – 9 mg/l), copper (0.03 – 0.04 mg/l), nitrate (31.9 – 39mg/l), and sulphate value between 11- 14mg/l, although, all these parameters fell within the standard values. However, Coliform as bacterial indicator was present in samples from asbestos, concrete and corrugated plastic roof, only the aluminium roof was free from pathogenic contamination. To ensure that the rainwater harvested satisfies health requirement for consumption as specified, all the harvested rainwater should be given some level of treatment in terms of pH, total hardness, chloride concentration and bacterial contamination. It was recommended that the rainwater from all the roofs in this case study area, be carefully examined. Consequently, if the harvested rainwater is being considered for domestic use, the gutters and the catchment areas should be regularly cleaned to remove animal droppings and leaves from over hanging trees as well as boiled to adequate temperature.

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