Rainwater harvesting is considered one of the most important water resources in the Palestinian countryside. Many studies in Palestine and around the world indicate that there is a probability that this harvested rainwater be contaminated with different pollutants, of which is "Heavy Metals", which are considered the most dangerous pollutants of drinking water. In this research, the study area chosen for the study was Yatta town in Hebron city. 75 water samples were collected from 75 cisterns in a number of neighborhoods in Yatta. An analysis for the samples was made in the laboratory of Al-quds university to test the existence of a number of heavy metals namely, Pb, Cr, Mn, Co, Ni, Cu, Zn and Cd.
The results were compared with the WHO and Palestinian limits for drinking water quality. Considering the metals Mn, Co, Cu and Cd. Neither of the samples exceeded any of the two limits. For the metals Pb, Cr, and Ni, two samples exceeded both limits. For the metal Zn, one sample exceeded the WHO limit only.
Sources of pollution by heavy metals of the harvested rainwater were identified by means of a questionnaire distributed on the households. Statistical analysis was made to identify sources of contamination by heavy metals by connecting the questionnaire factors, which are considered possible sources of heavy metal contamination, and the laboratory results. The results showed that except for nickel and the sources of water in the cistern factor, there is no direct relationship between the questionnaire factors and the existence of heavy metals beyond local and international limits. Based on the questionnaire and literature: Possible sources of lead and zinc are the roof, storage tanks, distribution systems and plumbing; possible sources of chromium are road dust, asbestos brakes and anthropogenic activities occurring around the house; a possible sources of nickel is leaching from metals in contact with harvested rainwater such as pipes and fittings which are used to collect the harvested rainwater.
Also, an assessment of the potential health risks due to contamination of the harvested rainwater by heavy metals was made for all the samples that exceeded either WHO limit or the Palestinian limit or both. The Chronic Daily Intake (CDI) and the Health Risk Index (HRI) were calculated. The assessment was made for both adults and children. The results showed that all the samples are considered safe (HRI <1), which means that there are no potential health risks on consumers.