Air-cooled heat rejection systems (air-cooled condensers, chillers and dry coolers) relies on dry bulb temperature which is generally between 5°C (41°F) and 15°C (59°F) higher than the wet bulb temperatures. Traditionally, large heat rejection systems use cooling tower or evaporative coolers in order to reduce the heat rejection equipment size as well as the overall energy consumption due to lower condensing temperatures. However, the water based corrosion, maintenance and health risks such as Legionella disease moved the industry towards less efficient dry heat rejection systems. By simply intermittently spraying water over a wired mesh area in front of the heat rejection surface against the direction of the air stream introduces wet bulb temperature during only peak high ambient periods. Adiabatic cooling process can be introduced using simple city main water into an air stream which rapidly evaporates and the hidden energy of water provides a cooler down stream air temperature as much as 10~25°C (20~30°F) lower than the incoming air. Lower air on temperature results in lower condensing temperature and therefore save as much as 30% peak power consumption by simple using water directly from the tap. The majority of the time the water presence remains with the sealed main water pipe and it is based on Total Waste principle. Hence, the health risk involved with a standing water reservoir as well as expensive chemical treatment requirement can be completely eliminated. Test sites of this new concept indicated between 20~35% peak electricity reduction for Air Cooled Chillers and Condensers. This concept can be considering as a simple DIY kit for both New and Retrofit applications. Hence, the potential for the energy saving and Carbon Emission reduction for the industry as a whole is significant and this can be achieved by simple using the tap water.