3. Results and Discussions
3.1. Weather Data Analysis
This study utilizes the past 30 years of daily rainfall data, which is the minimum requirements for most climate related studies, and selects the weather station in the center of Colombo City.
Average annual rainfall for Colombo City is 2302 mm. The long-term trend of this annual rainfall records shows that there is a slight increase (R2 = 0.146) with some record high rainfall values occurring in the recent past (Figure 2). Historical records show that Colombo City receives an adequate amount of rainfall for many water sources to thrive, including the RWH system. However,
there are more dry days than wet days in Colombo City, marking the importance of additional water