Membran forward osmosis (FO) berbahan dasar kitosan termodifikasi pati umbi janeng melalui ikat silang telah berhasil diaplikasikan untuk pembuatan kantong air minum. Membran modifikasi dipilih untuk diaplikasikan pada kantong air minum karena memiliki karakteristik dan kinerja yang lebih baik dibandingkan membran tanpa modifikasi. Membran modifikasi yang digunakan secara fisik tampak tipis, kuat, transparan, berwarna kekuningan, dan berpori rapat. Membran modifikasi memiliki ketebalan 0,035 mm, swelling degree 78,98%, porositas 54,36%, nilai kuat tarik 87,63 kgf/mm2, dan elongasi sebesar 16,08%. Kantong air minum dibuat dari tiga bahan utama, yaitu plastik polipropilen (PP), membran modifikasi, dan aluminium foil. Proses FO dilakukan selama 1 jam dengan variasi larutan penarik berupa fruktosa 3 M, sukrosa 3 M, dan campuran keduanya. Proses FO dilakukan terhadap dua larutan umpan, yaitu air payau dan air kotor. Setelah proses FO selama 1 jam, nilai fluks tertinggi diperoleh dari larutan penarik sukrosa 3 M dengan larutan umpan berupa air payau dan air kotor, yaitu 5,75 L/m2jam dan 8,5 L/m2jam dengan nilai rejeksi mendekti 100%. Berdasarkan hasil pengujian terhadap parameter pH, total dissolve solid (TDS), salinitas, daya hantar listrik (DHL), logam berat serta kandungan bakteri Escherichia coli (E. coli), diketahui bahwa air hasil proses FO memenuhi standar baku mutu air minum yang sesuai dengan PERMENKES No: 492/MENKES/Per/IV/2010. Membran kitosan termodifikasi pati umbi janeng dapat digunakan sebagai metode alternatif dalam pemurnian air payau dan air kotor untuk menghasilkan air bersih minum dalam keadaan darurat. Kata kunci: kantong air minum, membran forward osmosis, ikat silang, pemurnian air. The chitosan-based forward osmosis (FO) membrane modified by janeng tubers starch through cross-linking has been successfully applied to drinking water bags. Modified membranes chosen to be applied to drinking water bags because it has better characteristics and performance than unmodified membrane. Modified membranes physically appear thin, strong, transparent, yellowish, and tightly porous. The modified membrane has a thickness of 0.035 mm, swelling degree 78.98%, porosity of 54.36%, tensile strength 87.63 kgf/mm2, and elongation of 16.08%. Drinking water bags are made from three main components, there are polypropylene plastic (PP), modified membrane, and aluminum foil. FO process is carried out for 1 hour with a variation of the draw solution, there are 3 M fructose, 3 M sucrose, and mixture. FO process is carried out on two feed solutions, there are brackish water and dirty water. After 1 hour of the FO process, the highest flux value was obtained from the 3 M sucrose with feed solution consisting of brackish water and dirty water, which were 5.75 L/m2hour and 8.5 L/m2hour with rejection value close to 100%. Based on the test results on the pH parameters, total dissolve solid (TDS), salinity, electrical conductivity, heavy metals and Escherichia coli (E.coli) content, it is known that the water from the FO process meets the drinking water quality standards based on PERMENKES No: 492/MENKES/Per/IV/2010. The chitosan membrane modified by janeng tubers starch can be used as an alternative method in the purification of brackish water and dirty water to produce drinking water in an emergency. Key words: drinking water bag, forward osmosis membrane, cross-linking, water purification.