Water quality index assessment of toxicity in direct and roofs runoff rainwater in industrial and remote areas of Eastern Nigeria

Rainwater may be contaminated by leaching from roofing materials and industrial activities, rendering it unsuitable for potable use. In this study, the physico-chemical, microbiological and heavy metals parameters were investigated in harvested rainwater quality from various roof types in the urban and rural areas of Enugu State, Nigeria, between April-July, 2018. Metal compositions of asbestos, corrugated iron, Cameroun zinc, Stone-coated tiles and long span aluminium were also assessed. Thirty-six (36) harvested rainwater samples were forwarded to the laboratory after determination of pH, temperature, TDS and electrical conductivity at the point of collection. Titration, Electrometric and spectrophotometric methods of analysis were used. Results were compared with the WHO, USEPA and NSDWQ water quality standards. The weighted arithmetic method was obtained for the assessment of the water quality index. Results for heavy metals (mg/L) gave values which ranged from 0.00 to 0.20, metal concentrations (mg/kg) of digested roofs gave 0.00-63.78, and other parameters gave 6.50-7.60 for pH and Escherichia coli (no detection). The obtained results met the national and global standards except for a few samples. The WQI gave values which ranged from 3.00 to 78.46 and were rated excellent to very poor water quality. It was concluded that harvested rainwater should be treated before drinking.