Most of the world water problems such as flooding, drought, water shortage, water pollution, heat island are all related to rainwater. By proper rainwater management, we can reduce the risk of such problems and enhance the resilience. To solve the SDG for drinking water by rainwater harvesting, innovations in technical, economic and social aspects are necessary.

Due to climate change and urbanization, water shortage problems are increasing throughout the world in both developing and developed countries. Community based rainwater harvesting can be a good option to solve local problems.

Rainwater management is used to mitigate extreme rainfall events without increasing the capacity of existing sewer system, and to mitigate urban heat island problems. 

City of the future will be a city that collects and utilizes rainwater instead of draining rainwater under a law or regulation.

In 2015, the following activities have been done:

• Open a website for promoting rainwater harvesting and management (www.rainforall.org).
• Hold the 6th Int’l Rainwater Harvesting and Management Workshop at ASPIRE 2015 at Beijing on Sep 22 under the theme of Multi-Purpose Role of Rainwater Harvesting and Management.
• Sponsor two local rainwater harvesting workshops at Vietnam.
• Make annual report in the format of a newsletter at the end of the year.

Although Rainwater harvesting is gaining much interest, the promotion has been limited due to several disadvantages such as seasonal variation, related cost, etc. However, most of these problems can be solved by making the system with more than one purpose. These includes, dual water system with rainwater and groundwater, hybrid system of rainwater and greywater, hybrid system with rainwater and desalination, adding values of flooding mitigation and food production. One of the examples is the “Concave Green-Roof as Water-Energy-Food Nexus” which won the outstanding award at World Water Showcase on April 2015 at the 7th World Water Forum.