This study explores the enhancement of solar water heater efficiency through the combination of a nanofluid blend comprising TiO₂, graphene oxide, and carbon black nanoparticles. The experimental research, carried out in Upper Egypt at some point of August 2022, specializes in evaluating the thermal performance improvements ac-complished via the nanofluid in a passive solar water heating machine. The key goals include assessing temperature rise, sun strength absorption efficiency, and thermal conductivity upgrades. A locally assembled sun water heater prototype consisted of a primary tank storing 100 liters of water, a secondary tank containing the nanofluid mixture, and a solar collector with dimensions of 1.550 m x 0.8 m. The nanofluid, synthesized with manipulate of nanoparticle concentrations (TiO₂: 20 nm, graphene oxide: 50 nm, carbon black: 30 nm), turned into dispersed in deionized water and characterized for stability, nanoparticle length distribution, zeta ability, and thermal conductivity. Comparative analysis with traditional water-primarily based structures revealed widespread improvements in thermal overall performance. The nanoflu-id-more desirable system carried out a temperature upward thrust of 35°C compared to 29°C in traditional structures below comparable solar irradiance conditions (800 W/m²). This enhancement is attributed to the nanofluid's superior heat transfer prop-erties, validated through stable heat transfer coefficients and efficient energy absorp-tion (40% efficiency). The novelty of this work lies inside the synergistic use of more than one nanoparticle to enhance thermal conductivity and heat transfer efficiency in solar water heating systems. This research combines TiO₂, graphene oxide, and car-bon black to leverage their complementary properties. By demonstrating the effec-tiveness of nanofluids in enhancing solar water heater performance, this research contributes to the ongoing efforts to optimize renewable energy utilization. Future research directions include optimizing nanofluid compositions for different environ-mental conditions and scaling up production methods for commercial deployment.