"Pattenrai!! - Minami no Shima no Mizu Monogatari" is a 12-episode anime series that centers on the challenges faced by the residents of a small, remote island in southern Japan as they grapple with a severe water shortage. The story is set on an unnamed island where the primary source of water, a natural spring, has dried up due to prolonged drought. The island's inhabitants, who rely heavily on agriculture and fishing, are forced to confront the crisis head-on, as their livelihoods and way of life are threatened.

The protagonist, a young boy named Tatsuya, becomes deeply involved in the community's efforts to find a solution. Tatsuya is resourceful and determined, embodying the spirit of resilience that defines the islanders. Alongside him is his friend, a girl named Aoi, who is equally committed to helping the community. Together, they explore various methods to address the water crisis, from traditional techniques to innovative ideas, often clashing with older generations who are skeptical of change.

The narrative also introduces a group of engineers and scientists who arrive on the island to assist in constructing a desalination plant. Their presence sparks tension, as some islanders view their methods as intrusive and disconnected from the island's traditions. The series delves into the cultural and generational divides that emerge as the community debates how best to solve the crisis, balancing modern technology with respect for their heritage.

Throughout the series, the water shortage serves as a catalyst for exploring themes of community, perseverance, and the delicate relationship between humans and nature. The characters' struggles are portrayed with a sense of realism, highlighting the emotional and practical challenges of living in a resource-scarce environment. The story progresses through a series of trials and setbacks, culminating in a collaborative effort that underscores the importance of unity and adaptability in the face of adversity.