The present invention provides a thermal energy exchanger for bathing shower water comprising an upper deck, a lower chassis and two hatches. The upper deck features creased top surface, multiple parallel septa and plural heat conducting ribs being created between each pair of adjacent septa. After having assembled, the circulation of internal water tunnel is configured into a continual zigzag duct to increase energy saving effect in consequence of improvement in heat exchanging efficiency of the water heater. With simple structure, it is easily fabricated by traditional extruding method without welding process and related welding technician. Thereby, selling price is reduced with marketing competitiveness because overall manufacturing cost is decreased so that the purchasing intention of the consumers is spurred. Thus, it is not only favorable to promote and penetrate marketing range and depth but also valuable to achieve energy saving and carbon reducing effect.