The cause of flooding is rain water - use of rainwater is the best solution to solve the root problems of flooding and water shortage. Using rainwater to gradually replace or supplement the current water supply system is essential. This also ensures sustainable development for urban areas. In Vietnam, rainfall regime is unevenly distributed in both space and time. Therefore, using rainwater to completely replace the existing water supply system is not feasible. In this research, two demonstration models using rain water in combination with current water resources for the public sectors and households, and evaluate the effectiveness of the construction of the model.