Maybe in our daily life, we always unintentionally have these behaviours, such as taking a shower for 30 minutes, forgetting to turn off the water. We seldom think about the bad effect of these behaviours. In someone's mind, it feels like that water is an inexhaustible resource. But In another scene, a wheat standing in a field without drinking a drop of water for a few days. The sky is clear without any clouds. It hasn't been rainning for a month. In fact, it has a chance to be watered before, but the water from reservoir prioritized to provide for people who living in city. Maybe just one drop of water can help the wheat survives the drouth. Some people waste water every day, meanwhile the plants fight with the sun every day, too. This can be a win-win war at first. People save each drop of water, the water in a reservoir in enough to be provided for both people and plants, but finally they fails due to the people's greed and selfishness!