<![CDATA[Background: Access to microbiologically safe water is a critical challenge in post-disaster conditions, where surface water is often heavily contaminated by pathogenic microorganisms. Methods: This study adopts a comprehensive approach by first characterizing the microbiological load of post-flood well water using the Most Probable Number (MPN) method to establish filtration targets. Subsequently, a CA/PEG composite membrane was synthesized via a phase inversion technique, with PEG functioning as a porogen to enhance hydrophilicity. Five PEG loadings (1, 3, 5, 7, and 9% w/w) were screened using the immersion-precipitation phase inversion method; surface wettability was measured at five locations per membrane by the sessile drop method (5 µL deionised water, contact angle goniometer). The standard three-stage presumptive–confirmed–completed MPN procedure was applied to the collected post-flood well water samples. Findings: Field analysis of post-flood well water samples revealed a critical contamination level of 210 MPN/100 ml. In response, the synthesized 9% CA/PEG formulation was identified as the optimal core material, exhibiting superior super-hydrophilic properties (Contact Angle: 55.59°). Based on these material characteristics and the proposed multi-barrier design, the system is engineered to reduce Coliform contamination to <3.0 MPN/100 ml, complying with WHO and Indonesian standards (Permenkes No. 492/2010). Conclusion: As its primary contribution, this study formulates an evidence-based design for a portable water-filtration kit featuring a multilayer purification system consisting of a pre-filter, synthesized nanofiltration membrane, and UV sterilization as an integrated approach to producing microbiologically safe water. Novelty/Originality of this article: This conceptual design provides a strong scientific foundation for prototype development in subsequent research, while also demonstrating the potential of a technology that is not only technically effective but also aligned with the principle of Hifz al-Nafs within Maqashid al-Shariah and supportive of SDG 6 through the provision of a sustainable and accessible water-purification solution in emergency conditions. Note that the reported microbiological efficacy represents a projected design target; prototype-scale field validation remains the essential next step.]]>
