After Hurricane Harvey hit in 2017, Houston jumped to the front of the pack in adapting to the threat of climate change. It passed tougher building codes, offered more buyouts for flood-prone homes and budgeted billions of dollars in new funding for flood control.

When almost a month’s worth of rain deluged this city on Monday morning, turning streets into rivers and basements into wading pools, it showed just how vulnerable cities with aging water systems can be in the era of climate change.