ABSTRACT Mallari, Charlize Danielle B. May 2023. THE DETECTION OF Escherichia coli ON COMMUNITY WATER "POZO" IN SAN NICOLAS 2, MAGALANG, PAMPANGA. BACHELOR OF SCIENCE IN BIOLOGY. Pampanga State Agricultural University. Adviser: Cristel Joy C. Mallari, M.Sc. The study articulates the detection of Escherichia coli on communal water "pozo" that can possibly impose health risks on the residents due to contamination with fecal matter. The purpose of the study is to ensure the safety of the residents and prevent causing E.coli-related diseases; the improvement and monitoring of water quality and potability of water in communal water "pozo" of the selected communities, to provide baseline data for the policy makers towards the improvement and monitoring of common water sources; and to have a safe and sustainable management system of one of the most common water supplies to assess the quality and potability of water obtained from the community pozo in selected barangays of the municipality of Magalang, Pampanga. The sample site with the most number of cases in Magalang was established to be the San Nicolas where & samples per purok were collected. Multiple Tube Fermentation technique was used to detect the presence ofE. coli in the presumptive test 40 of the samples were positive, in the confirmative test, the samples with positive results were 13, and among the 13 positive samples in the confirmative test, 7 showed growth and also Puroks 4 and 5 detected the presence of E. coli in the sample collected. Thus performed the gram-staining technique to verify the isolated bacteria attained. Results revealed that the water sample from the Purok 2 had an MPN value of 8.0 indicating that the sample is not safe for human consumption. Hence, the regular monitoring of MPN values on communal water pozo is a viable option for policy makers to secure the health and safety of the community.