There is only so much water in the cup and the water must go to different plants. Some plants need more water than others and some don’t need to be watered each day. One can get a bigger cup but they still have the same amount of water but in a bigger cup. One must either decrease the number of plants or decrease the amount of water given to each plant. If this is done, than one can increase the amount of water in the cup. Perhaps, even to the point of it overflowing. Then it can be poured out to the other cups in need of more water. Save water.