A tunnel-type dishwasher comprising a water supply line for receiving clean water to be used in the dishwasher; a wash item entrance for receiving a feed of wash items to be washed by the dishwasher; a wash item exit for discharging said wash items when they have been washed by the dishwasher; a rinsing section upstream, with respect to a feed direction of said wash items, of the wash item exit; a main washing section upstream, with respect to said feed direction, of the rinsing section; a pre-washing section upstream, with respect to said feed direction, of the main washing section, the pre-washing section comprising a pre-washing sprayer for spraying a pre-washing liquid onto the wash items, a pre-washing liquid tank for pre-washing liquid that is to be sprayed from the pre-washing sprayer, and a pre-washing liquid inlet (58, 68) configured to receive liquid that has been used in the main washing and/or rinsing section(s) (14, 16); and $ a gas discharge flow heat exchanger; characterised in that the tunnel-type dishwasher comprises further a pre-washing liquid cooler for cooling the pre-washing liquid of the pre-washing liquid tank, wherein the pre-washing liquid cooler is configured as a pre-washing liquid heat exchanger arranged for exchanging heat between the clean water in the water supply line and the pre-washing liquid of the pre-washing liquid tank; and wherein the agas discharge flow heat exchanger is connected to the water supply line upstream, with regard to a flow direction of the water in the water supply line, of the pre-washing liquid heat exchanger, and configured to exchange heat between the supply water and a discharge flow of air and steam from the dishwasher. a water supply line for receiving clean water to be used in the dishwasher; a wash item entrance for receiving a feed of wash items to be washed by the dishwasher; a wash item exit for discharging said wash items when they have been washed by the dishwasher; a rinsing section upstream, with respect to a feed direction of said wash items, of the wash item exit; a main washing section upstream, with respect to said feed direction, of the rinsing section; a pre-washing section upstream, with respect to said feed direction, of the main washing section, the pre-washing section comprising a pre-washing sprayer for spraying a pre-washing liquid onto the wash items, a pre-washing liquid tank for pre-washing liquid that is to be sprayed from the pre-washing sprayer, and a pre-washing liquid inlet (58, 68) configured to receive liquid that has been used in the main washing and/or rinsing section(s) (14, 16); and $ a gas discharge flow heat exchanger; characterised in that the tunnel-type dishwasher comprises further a pre-washing liquid cooler for cooling the pre-washing liquid of the pre-washing liquid tank, wherein the pre-washing liquid cooler is configured as a pre-washing liquid heat exchanger arranged for exchanging heat between the clean water in the water supply line and the pre-washing liquid of the pre-washing liquid tank; and wherein the agas discharge flow heat exchanger is connected to the water supply line upstream, with regard to a flow direction of the water in the water supply line, of the pre-washing liquid heat exchanger, and configured to exchange heat between the supply water and a discharge flow of air and steam from the dishwasher.