_____________________________________________________________________________________________________ *Corresponding author: E-mail: hsabdelkader@uj.edu.sa, hsabdelkader@gmail.com; Journal of Pharmaceutical Research International 33(26A): 14-34, 2021; Article no.JPRI.67925 ISSN: 2456-9119 (Past name: British Journal of Pharmaceutical Research, Past ISSN: 2231-2919, NLM ID: 101631759) Disinfection of Tank Water Using Biogenic Silver Nanosilica as Anti-Microbial Agents in Jeddah City Hayam S. Abdelkader 1* and Nuha M. Alhazmi 1 1 Department of Biology, University of Jeddah, College of Science, Jeddah, Saudi Arabia. Authors’ contributions This work was carried out in collaboration between both authors. Authors HSA and NMA designed the study, performed the experiments and wrote the paper. All authors read and approved the final manuscript. Article Information DOI: 10.9734/JPRI/2021/v33i26A31468 Editor(s): (1) Dr. Aurora Martínez Romero, Juarez University, Mexico. Reviewers: (1) Gedif Meseret Abebe, Wolaita Sodo University, Ethiopia. (2) Juan Carlos Hernández González, Instituto de Ciencias Agropecuarias UAEH, Mexico. (3) Nayeli Shantal Castrejón-Jiménez, Instituto de Ciencias Agropecuarias UAEH, Mexico. Complete Peer review History: http://www.sdiarticle4.com/review-history/67925 Received 17 February 2021 Accepted 23 April 2021 Published 26 April 2021 ABSTRACT The need for clean water is becoming urgent all over the world. The risk of microbial contamination of drinking water and its growing ability under poor nutritional conditions occur frequently and existing water management systems do not efficiently eliminate these micropollutants. The major goal of this research is to analyze and test the drinking water quality at random locations in Jeddah City and to investigate the integration of polyurethane foam coated nano-silica silver nanoparticles (NSAgNPs) into the water purification system. The study was conducted in Jeddah city at random intervals during August to December 2020. Twenty-five samples (n = 25) of drinking water (tank water) were collected from different locations in Jeddah. The water samples were found contaminated with E. coli, Klebsiella pneumoniae. and the most prevalent yeast species was Candida albicans. The multi-drug resistance isolates were positively identified by PCR amplification of 16S rDNA gene fragments. The antimicrobial activity of nano-silica silver nanoparticles (NSAgNP) was analyzed and their optimal concentrations that remove potentially harmful microbes were determined. The cytotoxicity of NSAgNPs by Sulforhodamine B colorimetric (SRB) assay against breast adenocarcinoma cell line (MCF-7) showed no cytotoxic effect at concentrations ≤100 µg/mL. The 50% growth inhibition concentration (IC 50) of NSAgNPs after 72 h was 35.8 µg/mL. The excellent performance of NSAgNPs can be attributed to the capping surface functional groups Original Research Article