What does "the kitchen sink can't hold water" mean in Feng Shui?

What does feng shui mean by "the kitchen sink can't store water"? The water stored in the sink is unsanitary, and it is easy to produce bacteria with unknown truth. If it is clean water, temporary storage will not hinder it. But the sink must be used to wash dishes. Why does it need to store water for a long time? Is there any pattern?