Rainwater is essential in the sustenance of ecosystem in all parts of the world. It is a free source of nearly pure water and naturally replenishes the earth’s water supply. On the other hand, tap water is one of the most available types of water intended for human consumption while rainwater serves many purposes too. This study aimed to assess the quality of tap water and rainwater in Davao City, specifically in Agdao, Ecoland and Artiaga. The proponents used plant growth of selected varieties such as mongo, radish, tomato, eggplant, and squash, as the main parameter in comparing the rainwater and tap water after 30 days; pH, conductivity, and Total Dissolved Solids (TDS) were also used as additional parameters, which were determined at the Science Resource Center of the University of the Immaculate Conception. This study employed of a descriptive – comparative design making use of quantitative measurements and data from laboratory analyses. The results revealed that rainwater and tap water in Davao city are both safe for plant growth as indicated by the values of the parameters which are within the acceptable range describing a good quality for growing plants.