Sustainable utilization and conservation of natural resources has a key importance in intelligent development. To attain sustainable utilization and conservation of water resources, it is vital to discover and implement alternative and non-conventional resources and methods of water supply to various sectors. One of alternative methods of supplying water for household consumption which has been historically practiced in many parts of the world, particularly in arid and semi-arid regions of Iran, is rooftop rainwater harvesting and storage in cisterns. Although rainwater harvesting is considered as an interesting and effective means of water resource management, numerus limitations such as climatic variability, irregular rainfall pattern, insufficient storage space, financial incapability, health issues, legal and regulatory restriction, and lack of installation and maintenance services hinder the adoption and expansion of rainwater harvesting systems among societies. Both preparing and enacting of compulsory laws and regulations and offering incentives is necessary for widespread adoption of rainwater harvesting. To this end, many countries, mainly arid and semi-arid countries and recently countries with temperate or even humid climates, have made and implemented policies regarding water conservation and supply through alternative methods. These countries have developed laws and regulation as well as financial incentives. A review of the experiences of these countries, which is the aim of this paper, will benefit policy making for rainwater harvesting in Iran. Therefore, in this paper the rainwater harvesting programs, projects, laws and regulations in USA, Germany, Australia, Brazil, China, Malaysia, India, Japan, Thailand, Barbados, and Kenya are briefly introduced as examples.