Toxic elements (heavy metals) generally include a wide range of elements such as cadmium, lead, arsenic, etc. which have a significant impact on water pollution, especially human drinking water. The main purpose of this study is to investigate the effect of these metals on the level of drinking water pollution in Iran. This research is a systematic review article, conducted by searching the Scholar, SID, Science Direct, PubMed, and MAGIRAN databases for related published papers from 2000 to 2019. Several keywords have been searched including heavy metals, drinking water, water pollution index, urban water supply network, and GIS. Searching the database, 812 articles have been found, out of which 190 articles were picked out by reviewing their titles and abstracts, and finally, 50 articles were selected by reading the entire text. Out of these 50 articles, 25 articles were selected for review due to their high conceptual relationship with this study. According to the results, in 54.17% of the studies, the concentration of heavy metals was higher than the standards of Iran and WHO. The concentration of toxic elements Chromium, Arsenic, Cadmium, Lead, Copper, Iron and Manganese, in 18.75, 30, 16.66, 33.33, 7.69, 33.33 and 25% of the articles were higher than the permissible limits, respectively. In general, natural factors such as geology and human factors such as the effects of effluent, waste, metal and worn water supply networks caused pollution in drinking water.
