ABSTRACT SIH, MIKE ANGELO B. December 2022. "Bacteriological and Physicochemical Assessment of Bottled Drinking Water in the First District of Bulacan, Philippines." Master of Science in Biology. Pampanga State Agricultural University, Magalang, Pampanga. Adviser: JACQUELINE V. BAGUNU, Ph.D. The quality of drinking water has consistently been a Significant health concern. In most countries, it is often considered that bottled water is safe for usage by everyone. However, various studies have stated that bottled water does not constantly meet the required standards for safe drinking water. This study aimed to assess the bacteriological and physicochemical qualities of locally available bottled drinking water in the First District of Bulacan, Philippines, to check its compliance with national standards. A cross-sectional study was carried out with a total of nine samples collected. These comprised three samples collected from the different drinking water stores in Calumpit, Pulilan, and the City of Malolos using stratified random sampling. Samples were analyzed using standard methods, and the results were compared with the prescribed national standards for drinking water quality. The results revealed that the bacteriological and physicochemical parameters of all bottled drinking water samples passed the quality standards for drinking water. It is recommended that continuous surveillance and monitoring in the production of bottled drinking water must be done to ensure the consistency of the quality of the bottled drinking water for maximum safety and healthy living for ail. Awareness should also be given to the public regarding the potential health problems of using untreated water for human consumption. Key words: bacteriological, physicochemical, bottled drinking water, small-scale water refilling station