Rainwater harvesting is a method of capturing the rainfall to meet water requirement in both urban and rural areas. Urban population growth and reduction of water reserved in Selangor has allowed the government to promote the rainwater harvesting system as an alternative resource among consumers. This paper attempts to examine rainwater harvesting system at the experimental site of Bandar Baru Bangi, based on several episodes of rain variations recorded from December 2014 to April 2015. The observation data being used to identify the relationship between the local rainfall and the potential volume variation of the harvested water. The experimental results revealed that the harvested volume varies, from the lowest value of 0.018 m³ to the highest of 2.722 m³. The relationship between harvested volume and the depth of rainfall produced significant R² value (R² = 89%). The study also proved that the volume of storage tank (1000 litres) at the experimental site is suitable with rainwater harvesting variation.