I remember a story where the uni housing didn't have fresh water, but boiling water stations. So a student had to go from one building to another to get fresh water to drink, since their water was cut off (10 story building). Same as the Chinese trains I travelled. By the time she got back to the room with the sick person, she had time to poison the water she retrieved to give....

The whole of China is possessed with a belief murders are not traceable.