Heat exchanger for a waste water plant

The invention relates to a heat exchanger (100) for connecting to a sewage system, consisting of a sewer line (200) having an inlet port (211) and a drain port (221). Further, a fresh water dispenser (300) with a fresh water inlet (310) and a hot water port (321) in the heat exchanger (100) is provided. The heat exchanger (100) is provided for deviating from the horizontal mounting with a slight downward inclination to the horizontal in a waste water flow direction (204). Thus, waste water can flow in the abdomen of the sewer pipe at a moderate speed. The fresh water distributor (300) I-tight manner with a good heat transfer with a belly of the sewer pipe (200), where at least a flow space for fresh water through at least two fresh water pipes (301, 302, 303. 304, 305) are formed in the region of the abdomen. In the flow space a pressurized fresh water in countercurrent to the waste water can through the fresh water pipe (301, 302, 303, 304, 305) flow at a moderate gradient in a fresh water flow direction (306).