Large amounts of low-caloric heat are wasted every day in our wastewater. The discharge of large, energy consuming industries such as the UPM-Kymmene paper- mill in Augsburg has an average temperature of 35C, yet the huge heating potential is inadequately investigated. Data acquisition from UPM and the municipal wastewater treatment plant are essential to evaluate the exact amount of useful heat. The best technical and economically most feasible solutions for the heat recovery from wastewater are discussed. Characteristics of the wastewater from the paper machines favour inexpensive plate heat exchangers to heat freshwater from the borehole for the paper production process. A temperature reduction of the wastewater by 5C results in an annual heat recovery of 7.9 GWh and 11.6 GWh for the two paper machines. The utilisation of this low-caloric energy source can reduce the overall primary energy demand of the paper-mill by 1%, which equals to annual savings of approximately 200,000 m3 of gas and respectively 5,000 t of CO2 immissions. This potential, otherwise wasted in the canalisation can also be used in combination with a heat pump to cover heating and cooling demand. Projects of that type show economic and ecological benefits and Augsburg definitely has excellent potential with minor risks.