To address the challenges of the energy transition, reducing consumption and optimizing energy production is crucial for all industrial sectors. In the future, water issues will be as important as energy issues, making the optimization of water supply systems critical. The water sector represents large energy consumption for pumping and heating. In regards to this consumption, water systems have a great potential for energy recovery through hydroelectric production or thermal energy recovery. This article aims to quantify the energy potential of water supply systems, which has not been well understood until now. The energy potential of these systems encompasses hydropower recovery and thermal potential, including heat recovery and cold recovery. For that, a method is developed to estimate this potential, including the recoverable power, its location, and its temporal variation. The method can be used for hydroelectricity production, as well as for heat and cold recovery. For a whole year, the results indicate a hydraulic potential of 15 MWh.km−1.year−1, and respectively 1650 MWh.km−1 .year−1 for heat recovery and 766 MWh.km−1.year−1 for cold recovery.