Quality assessment and public health status of harvested rainwater in a peri-urban community in Edo State of Nigeria

The harvested rainwater is an alternative water source in communities where there is limited or scarcity of water distribution system. However, contamination of roof-harvested rainwater is of immense concern to the general public health. Therefore, this study was initiated to assess the levels of physicochemical quality and heavy metal concentrations in the harvested rainwater from Oluku communities in Benin City, Edo State, Nigeria. The roof-harvested rainwater samples were collected from 20 independent different residential households in Oluku communities, between April 2015 and September 2015. Physicochemical analyses were carried out using standard analytical methods, and heavy metal concentrations were determined using atomic absorption spectrophotometry. The evaluation of the rainwater harvesting shows that 60% (12/20) of the roofs were made of corrugated iron sheets; aluminum sheets, 20%(4/20); asbestos, 10%(2/20); and open space was 10% (2/20). Also, the storage systems used for the storage of harvested rainwater were as follows: PVC tanks, 20% (4/20); drums, 30% (6/20); buckets, 25% (5/20); and wells, 25% (5/20). The physicochemical indicators investigated (temperature, nitrate, chlorine content, electrical conductivity, phosphate, total dissolved solids, and sulfate) were within World Health Organization (WHO) guidelines. However, some pH levels of the roof-harvested rainwater were acidic and below the WHO standard. Furthermore, a high value of turbidity was observed in some locations and exceeded the WHO guidelines. Though some heavy metal indicators (Zn, Na, K, and Ca) in this study were within the WHO guidelines, some locations revealed heavy metal (Cu, Fe, and Cd) concentrations slightly above the WHO guidelines. There is need for proper rainwater harvesting system and continuous monitoring of harvested rainwater for potable uses.