The recent reputational excellence of triboelectric nanogenerators is based on the idea that they have overcome many limitations for traditional energy harvesting methods. However, in many important respects, these nanogenerators show little promise in addressing the limitations of device efficiency, and in some cases, they threaten the material lifetime. To overcome both efficiency and durability issues, we propose a novel mechanism that generates a DC output via water electrification based on phase control to enhance the sustainability of nanogenerators. Our demonstrations here can enable breakthrough impacts by enhancing device durability with fluid control, generating DC output for energy-loss reduction and providing feasibility with an application model. The advantages of our fluid-controllable DC power nanogenerator can be integrated easily with every energy-harvesting device, thus making it easy for energy-related disciplines to overcome major issues in the more practical way.