The Wayward Cloud (2005) on Netflix

Plot summary

A drought has hit Taiwan, and watermelons are plentiful. Television programs demonstrate ways to save water and urge people to drink watermelon juice instead. Hsiao-kang appears in pornographic movies, shooting scenes that use water and the fruit. Shiang-chyi collects discarded bottles, and one day she spots watermelons in a river, takes one, and, passing Hsiao-kang asleep on a bench, rinses it with water from his bottle. He wakes, and the two recognize each other from the time he sold watches. She has no idea what his work is now. They begin spending time together, sharing watermelon and meals, and song-and-dance numbers break into their days.