Climate change and increasing water scarcity necessitate the adoption of efficient water management strategies in agriculture to enhance crop productivity and sustainability. This study comparatively evaluates the growth performance and water-use efficiency of mustard (Brassica juncea) cultivated under three systems: Nutrient Film Technique (NFT), Deep Water Culture (DWC) hydroponics, and conventional Soil-Based (SB) cultivation. Mustard seedlings were transplanted into each system; hydroponic setups were supplied with Hoagland’s nutrient solution (EC 2.0 mS cm⁻¹, pH 6.0), while the SB system utilized standard fertilization and irrigation. Key growth parameters, including number of leaves (NL), stem diameter (SD), shoot length (SL), root length (RL), and plant height (PH), were statistically analyzed alongside total water consumption per plant. Results demonstrated that the NFT system significantly outperformed both DWC and SB systems, achieving the highest plant height (42.2 cm), shoot length (25.8 cm), root length (16.4 cm), and stem diameter (1.8 cm), while using only 3.2 liters of water per plant. DWC showed moderate growth (PH: 35.6 cm; SL: 21.4 cm; RL: 12.3 cm; water use: 5.8 L/plant), while SB showed the lowest growth performance (PH: 29.1 cm; SL: 17.6 cm; RL: 10.1 cm; water use: 8.5 L/plant), primarily due to inconsistent moisture and nutrient availability. These findings confirm the superior water-use efficiency and biomass productivity of the NFT system, underscoring its potential as a sustainable, climate-smart solution for resource-limited agricultural settings.