Flying 343 km above the Earth, the pair of astronauts for China's second manned space mission aboard Shenzhou-6 spacecraft drink water that comes from 1,700 meters underground.
Chen Bin, director of the aerospace food and nutrition office of the China Space Center, said that in comparison with the mineral water on the market which is generally got from 100 meters underground, what astronauts Fei Junlong and Nie Haisheng drink can be called China's "purest" water.
Coming from a depth of 1,700 meters, the unpolluted water has the lowest content of foreign substances and no microelements are added after depuration. It is 99.99999 percent pure, he said.
Like Russia, China uses electrolytic silver solution to disinfect astronaut's drinking water. Only 0.2 milligram of silver remains in one liter of water after the process, harmless to human body at such low level, and the water stays drinkable for three months.