Rainwater harvesting can help solve water scarcity issues in Bangladesh by collecting rainwater for domestic use. A study developed guidelines for sizing storage cisterns based on existing data, creating a computer program and animation to demonstrate the system's construction and benefits. The goal was to find a sustainable rainwater harvesting solution for multistoried residential apartments in Dhaka, Bangladesh. The study analyzed different methods of rainwater harvesting in Bangladesh, highlighted its importance in urban areas, and proposed a solution for a typical residential building in Dhaka.