Assessments of Roof-Harvested Rainwater in Disctrict Dir Lower, Khyber Pakhtunkhwa Pakistan

Abstract

The main objective of this study was to assess the quality and quantity of roof-harvested rainwater to overcome the water shortage problem in the study area. We also aimed to find health hazards associated with rainwater in the study area. For this purpose, rainwater samples were collected from five sites in the study area. The samples were analyzed using standard methods of the World Health Organization and the American Public Health Association in a laboratory. The analysis showed that all the physicochemical parameters were within the permissible limits of the WHO’s guidelines except pH, turbidity, and some trace metals such as iron (Fe) and lead (Pb). The mean values of pH range from 5.18 to 6.26, indicating slight acidity, while the highest mean turbidity was found at 5.77 NTU. Similarly, the highest mean concentrations of Fe and Pb were 0.95 mg/L and 0.056 mg/L, respectively, which was above the permissible limit of the WHO’s guidelines for drinking water. The annual rainwater-harvesting potential was assessed using the formula annual rainfall × roof area× runoff coefficient. The annual rainwater-harvesting potential of the study area was 56.803 L per household. At the same time, the average monthly rainwater-harvesting potential was 4733 L in the study area. This shows the potential for roof-harvested rainwater in the study area. A risk assessment of heavy metals showed that the rainwater of the study area is safe and does not pose any risk. This study concludes that rainwater is suitable for drinking and other domestic consumption if proper care is taken to clean the roof area and storage system and divert the first flush from the storage system.