To provide desalting fresh water making facilitaties capable of transporting fresh water to an inland area simultaneously with the desalting production of fresh water without using fossil fuel, and a method for forming low-vacuum state therein.

A highly airtight pipe is installed in the area from raw water 5 such as saline water to the inland area 7 expected in a fall in atmospheric temperature in the night and the gas other than steam in the pipe is wholly extracted. Whereupon, the raw water is evaporated (boiled) in an evaporation part 1 to fill the pipe with steam. Especially, since the temperature of an adiabatic transport part 2-1 is made lower than that of the evaporation part 1 in the night, steam flows in a radiation transport part 2-2 by the pressure difference in the pipe but, since steam corresponding to an amount exceeding the saturated amount of steam can not be present in a gaseous state, a part of steam is condensed in the radiation transport part 2-2 and fresh water is refined. However, if the temperature difference between the evaporation part 1 and the 2-2 is eliminated, the refining of fresh water is stopped. Accordingly, the fall in temperature is suppressed in the evaporation part 1 by the circulation of raw water and the temperature rise in the radiatioan transport part 2-2 is suppressed by reducing a heat flux.