Water is a useful resource. No one can live without water. Water can make people live. Used water can be used to water plants, clean rooms and so on. In recent years, water resources are in short supply, which is due to human destruction. They throw used things everywhere, making the river so dirty. Now, we must take measures to save water. We should recycle water and don't throw used things into rivers or lakes. In addition, we should call more people to take part in this activity to save water. What's more, we should set an example.