eng Science and Education Publishing American Journal of Public Health Research 2327-6703 2025-04-27 13 2 86 89 10.12691/ajphr-13-2-8 AJPHR20251328 article Siri Muppidi 1 Ryan Clark PhD MSc ryanclark@msm.edu 1 Morehouse School of Medicine, Atlanta, USA Poor access to clean drinking water is responsible for millions of water-borne disease deaths each year and is a critical issue worldwide. Because most household water filters are not antibacterial, impure drinking water disproportionately impacts communities with poor public water treatment. Chitosan is an abundant natural biopolymer that has remarkable antibiotic properties due to its molecular structure. An antibacterial water filter was developed by adsorbing two molecular weights of chitosan onto activated carbon (AC) to synthesize novel compounds which effectively deliver chitosan for water treatment. An in vitro evaluation of the filter¡¯s antibacterial properties was performed by measuring Colony Forming Units (CFUs) in the water sample. Additionally, a Kirby-Bauer Disk Diffusion Susceptibility Test was used to distinguish between the efficacies of high molecular weight chitosan (HMWC) and low molecular weight chitosan (LMWC). Based on inhibition zone measurements, it was determined that HMWC is most effective at eliminating bacteria from contaminated water. Water purified using the HMWC filter had bacterial growth of 0 colonies/mL, whereas the control sample contained 7600 colonies/mL, indicating a 100% statistical reduction. The chitosan-AC compound filter developed in this experiment has several practical applications and can be used to enhance the performance of traditional household water filters used worldwide. This innovative, low-cost filter may also be used during emergencies and natural disasters as well as in the military. Furthermore, since chitosan is derived from nature and is biodegradable unlike synthetic antibiotics, its use does not contribute to environmental pollution or antimicrobial resistance. https://pubs.sciepub.com/ajphr/13/2/8/ajphr-13-2-8.pdf Low Molecular Weight Chitosan High Molecular Weight Chitosan Colony Forming Units Zone of inhibition