When rain falls in Los Angeles, most of it flows away–despite how desperately the city needs water. As the drought continues, and as climate change threatens future water supplies, some experts think the city needs to be fully redesigned to soak up stormwater block by block.

Right now, the city is set up to get water from formerly snow-filled mountains that are warming up.

“We’re not designed for rain in the west,” says Hadley Arnold, co-founder of the Arid Lands Institute, a nonprofit and research at Woodbury University that is working on tools to help redesign the area’s approach to water. “We capture snow, and dispose of rain. So in a changing hydrologic cycle where there’s less snow, rain has more value, and we need to figure out how we’re going to grab it.”

Scott Jezzard, Angelito Villanueva, Bianca Bouwer/Perkins+Will

Capturing more rain would solve another problem–the huge amounts of energy that are currently used to pump water to L.A. “We’re using a lot of gas and coal to deliver our water to Los Angeles–and places like San Diego, Phoenix, Denver, and Las Vegas–which only exacerbates the problem,” Arnold says. “We warm the atmosphere further by trying to get these diminished snow resources. So how do you uncouple water from energy? That’s a design question.”

Right now, stormwater flows down roofs, roads, and parking lots and into drains leading to the ocean or the concrete-covered L.A. River. The Arid Lands Institute envisions turning the city into a giant sponge instead, where each building and yard can collect rain in a decentralized network.

They’ve created a new tool to help designers figure out how to optimize every house, apartment building, and street for rain. “It takes data from a lot of other disciplines that architects wouldn’t have access to or necessarily an interest in, and gives us a kind of martial plan for the city,” Arnold says.

David Bradshaw, Laura Arreola/Perkins+Will

The tool maps out the city into zones. Some areas can collect water; others can store it above-ground, because of pollution issues; and a third zone is only suited to send water somewhere else. Even within a neighborhood, zones can change, and the tool can tell an architect or homeowner exactly what they should do.