The water quality of 100 cisterns in Hebron city- Palestine was studied through the period from December, 2007 till April, 2008. Water samples were collected directly from cisterns in two sterile glass bottles and tested for physical parameters (electrical conductivity, salinity, total dissolved substances, pH, temperature and turbidity), chemical parameters (alkalinity, chloride, total hardness, calcium, magnesium, ammonia and nitrate), microbiological parameters ( total coliform(TC) and faecal coliform(FC)). All the results of physical parameters are within the acceptable limits of WHO, EPA and Palestinian standards except turbidity which exceed these limits in 24 % of the cases. The percentage of contamination of total coliform and faecal coliform was 95%, 57%, respectively. The chemical parameters exceed the standards by different percentages (calcium 47%, magnesium 32%), other parameters give results below the maximum contaminant levels. Sources of pollution of these cisterns were studied also by a questionnaire answered by the owner of the cistern..