MUMBAI, India — For many of the poor in this city, each year contains just two seasons: the demolition season and the rain.

Every winter, when Mumbai is dry, the police come with wrecking crews and rip down countless slum homes.

And every summer, when the monsoon hits, many of these same areas get flooded. Filthy water, swirling with oil stains, rushes into houses and sweeps away the few possessions, leaving behind plastic bottles, coconut husks, rocks, sticks and bundles of rags.