In recent years wireless sensors are becoming more widely used to monitor water distribution systems in the water supply industry. When sensors are installed in areas where electric power supply is lacking and/or battery replacement is difficult, harvesting renewable energy from the water distribution systems or the environment would be an attractive option. This work studies the feasibility of energy harvesting in water distribution systems from hydraulic energy in bypass water pipes, thermal energy in the water-air temperature gradient, and kinetic energy in the water pressure fluctuation. The energy harvesting systems are modeled and then analyzed by using simulated data and real data. The hydrothermal energy harvester and the water pressure fluctuation energy harvester introduced in this paper may be able to generate mW's power. DOI: 10.1061/(ASCE)EY.1943-7897.0000057. (C) 2012 American Society of Civil Engineers.