The International Rainwater Catchment Systems Association (IRCSA) aims to promote and advance rainwater catchment systems technology with respect to planning, development, management, science, technology, research and education worldwide; establish an international forum for scientists, engineers, educators, administrators and those concerned in this field; draft international guidelines on this technology and update and disseminate information; collaborate with and support international programmes.

It was founded August 1989 at the 4th International Rainwater Cistern Systems Conference in Manila and officially launched in August 1991 at the 5th conference in Taiwan. The association has since run conferences every two years; in Kenya 1993, Beijing 1995, Iran Islamic Rep 1997, Brazil 1999, Germany 2001, Mexico 2003, India 2005, Australia 2007, Malasia 2009 and  Taiwan, 2011. The next conference will be held in 2013 in Nanjing, China.

The primary objectives of IRCSA are:

1. The promotion and advancement of Rainwater Catchment Systems Technology with respect to planning, development, management, science, technology, research and education world-wide.  
2. The establishment of an International forum for scientists, engineers, educators, administrators and all others who are, directly or indirectly, concerned in rainwater catchment system programs to link all those working in this field so that information and experiences can be shared. 
3. The drafting of international guidelines on the use of Rainwater Catchment Systems technology and the updating and dissemination of this information. 
4. The collaboration with and support of International Programs in the field of Rainwater Catchment Systems including co-operation with other organizations having activities in common. 
5. The support and continuation of the International Rainwater Catchment Systems Conference series.