People have been living in illegal, unsafe basement apartments in New York City forever. Often, because it’s all they can afford.

In early September, more than a dozen people died in those apartments, when the remnants of Hurricane Ida dumped a record amount of rain in the city in an hour, and caused severe flash flooding. Many more lost everything. Most of them were low-income, and most were immigrants. 

“What we learned from Ida is that this affordable housing crisis intersects greatly now with the climate crisis,” said Rebekah Morris, senior program manager at the Pratt Center for Community Development, which has been working for years on a campaign to legalize more basement apartments and make them safer. 

Before the storm, the focus had mostly been on fire.  

“Because that was usually what was considered the biggest safety issue,” Morris said. 

Fire, and the risk of coastal flooding in low-lying areas near the water.  

“But what we saw with Ida was that it wasn’t just coastal storm flooding that we had to worry about, but also flooding from rain itself,” said Jessica Katz, executive director of the nonprofit Citizens Housing and Planning Council.

By some estimates, up to 100,000 New Yorkers are living in illegal basement apartments. And because they’re illegal, no one knows where they all are. 

The first step toward making them safer, is figuring that out, Katz said, “so that if there were a flood coming and an evacuation was necessary, we would know who to speak to about that.”

But, she added, the city also needs to make it easier and cheaper for people who own basement apartments to bring them up to code. 

“The hard part about basements is that there’s so many different overlapping regulations that it makes it very hard to comply and very expensive to comply,” Katz said. 

And some of them — around ceiling height or parking space requirements — have nothing to do with safety. 

“So if you could pare back requirements around parking and ceiling height,” she said, “then you could focus your efforts on safety measures around egress, pumps perhaps, and other types of flood proofing.”

Such as doors and windows that seal well, and emergency flood barriers. 

“We can certainly upgrade and make sure basement apartments are up to code, and even think about how code could shift to better protect basement apartments from flooding, but there’s no getting around the fact that water flows downhill,” said Timon McPhearson, director of the Urban Systems Lab at the New School, and a member of the New York City Panel on Climate Change.

“When there’s significant water flowing along the streets and on the sidewalks, it’s going to go down into any opening it can, and there’s a limited amount of our ability to stop that.”

The only real, long-term solutions, according to McPhearson, are to build affordable housing that’s not so vulnerable to flooding, and update the city’s storm water infrastructure so it can better handle torrential rain.

“We need to completely rethink the role of streets in managing storm water, and actually see them as part of an urban watershed that we can actually manipulate to reduce risk,” said Rob Freudenberg, vice president for Energy and Environment at the nonprofit Regional Plan Association. 

“We could do more to capture it with green infrastructure, absorb it with permeable surfaces, and divert it to places like parks, open spaces and other flood-able areas that keep water out of the places we don’t want it.”

New York City is already doing some of that, Freudenberg said, “we just need to do more of it in more places, and quicker” – starting with neighborhoods that are most prone to flooding.