There is a long-standing dispute between Iran and Afghanistan over the Helmand River. In recent years, between 2002 and 2013, the access to water of the population living in the river basin in Iran has been adversely affected. As the human right to water is recognized at the international level, this paper aims to study the national implementation of the human right to water in both countries. It analyzes Afghanistan's and Iran's legislation, regulation, adopted strategies and policies at the national level. It further assesses if there is an extraterritorial obligation for both countries to respect, protect, and fulfill the human right to water. Finally, it to proposes solutions that would contribute to the fulfillment of the human right to water.