What does Feng Shui mean by "no water should be stored in the kitchen sink"?

What does Feng Shui mean by "Don't store water in the sink of a house"? --- Storing water in the sink is unhygienic and can easily breed unknown germs. If it is dry, clean water, temporary storage is not a problem. But the sink must be used for washing dishes, so why does it need to store water for a long time? There are no rules.