Abstract
Rainwater for potable uses has increased in developing countries due to population increase and the failure of conventional means of water supply. However, the quality of roof harvested rainwater and its health implication are issues that require urgent attention. The quality of rainwater harvested from galvanized roofing sheets (GRS) of different ages was investigated. Rainwater samples were collected on monthly basis from roofs of 5, 10 and 15 years between July and September and for three consecutive years. The samples were analysed using standard methods for physical, chemical and microbial parameters. A comparison of means was done using the Duncan Multiple Range Test (p < 0.05). The water quality results were compared with 3 established standards (NSDWQ, 2007; WHO, 2011 and USEPA, 2012) for drinking water. There was no significant difference in the quality of harvested rainwater from roof of different ages. The pH of the samples fall within the standard range of 6.5 to 8.5, while an average of 41.96 mg/L for total hardness is far below the minimum permissible value of 150 mg/L. The Lead concentration which ranges between 0.0033 and 0.0055 mg/L is also below the permissible range of 0.01to 0.015 mg/L. The feacal coliform Escherichia coli count of 0 cfu/ml does not show biological contamination and is in tandem with the standards. However, treatment may be required for total coliform count as indicated in NSDWQ (2007). It is concluded that rainwater harvested from GRS of different ages in Ogbomoso, Southwest Nigeria is of a quality which does not have or indicate serious health impact.
Key words: Rainwater harvesting, alternative water sources, water security, water quality, roofs age, public health, Nigeria, Africa.
