Homes previously considered as less at risk of flooding face new danger due to climate change

Millions of Americans across the country faced devastating flooding from Hurricane Ida this week and are grappling with the risks a new reality poses to their homes.

With more humans building into nature, the fragile interface between weather extremes and the comfort of our homes is becoming more frequent. More than ever, it's clear that climate change is impacting everywhere we live.

Climate risk nonprofit First Street Foundation has found that 14.6 million American properties are at risk of flood. Six million of those don't make it on Federal Emergency Management Agency standards maps.

Joe Tirone was one of hundreds in Staten Island who lost their home in Superstorm Sandy in 2012. It's hard to imagine that where a marsh stands now, there were once several streets full of homes.

He was part of one of the biggest post-storm buyouts in history -- meaning he got reimbursed for the full value of his home.

"You're getting federal money, but it's run by the state," he explained. "It's a little bit complicated, but a miracle. ... No other place had done that."

Since then, he's led a push for more transparency, saying people need to know if a home they're going to buy has a chance of flooding. He pointed to the ability to see a pre-owned car's history before buying.

"Why isn't there a Carfax for houses? And that got me on a roll where I felt that there really should be more advocacy for homeowners or buyers," Tirone said. "As a realtor for over 20 years, I believe that we bring a lot of value to any transaction. So to me, it makes perfect sense for us to be the gatekeepers there as far as flood disclosure is concerned."

Michael Lopes, communications director at the First Street Foundation, said homes at risk of flooding can be at inland or "very high elevations ... places in the Pacific Northwest, places that people had never really thought of as being at significant flood risk."

"The flooding we saw in Tennessee and in Kentucky was shocking to people who just never really experienced this kind of flooding before," he said.

First Street Foundation takes a step beyond FEMA when assessing whether or not a particular property will flood. They factor in climate change.

"We're using the 4.5 curve, kind of a middle-of-the-road curve, not the most dramatic, not the least trying to give a sense of how that risk is changing over time," he said. "Something like heavy rainstorms are just becoming more frequent."

FEMA says having flood insurance is crucial for flood-prone areas because most homeowners policies don't cover it. There is a government-run flood insurance program, but it is far from perfect.

"You have middle and lower, middle-income people essentially subsidizing very, very, very wealthy people right now on the coast," Lopes said.

That's about to change with a government program called Risk Rating 2.0, which takes effect Oct. 1.

"We're going to be doing a much better job of clearly identifying flood risk and we're going to be able to price it fairly," David Maurstad, FEMA deputy associate administrator for federal insurance and mitigation and senior executive of the flood insurance program, told ABC News. "Currently lower-value homes are paying more than they should and higher-value homes are paying less than they should and Risk Rating 2.0 equity and action changes that inequity."

FEMA says even 1 inch of water can do $25,000 worth of damage to a home. Just because you aren't in one of those high-risk areas doesn't mean you can't have a serious flood.

"Hurricane Harvey, for example ... over 75% of the properties that are damaged were outside the high-risk area," Maurstad said. "Many of them did not have the flood insurance coverage that they need[ed]. And that's why equity and action is ... going to be so valuable -- because it's going to be able to indicate to people you are at risk, regardless of whether you're in a particular zone or not."

Many Americans rent and don't plan on buying their home. Lower-income neighborhoods tend to have higher burdens when it comes to climate change.

Real estate brokerage Redfin's own research found that flooding is worse in neighborhoods that have been historically redlined, a term for areas where people are refused a loan due to financial risk. When a Black, brown or poor white town is hit by a storm, the community struggles to recover.

"Disasters contribute to widening equality gap in the United States, you know, especially when you're looking at it from a financial perspective," said Rob Moore, senior policy analyst at the Natural Resources Defense Council. "Poorer people tend to become poorer in the aftermath of a disaster and more-affluent people tend to either stay the same, or in a perverse way, they actually can actually gain financially."

Even if you don't think you are in an area that can flood, think again.

"Where it can rain, it can flood," Maurstad said. "Ninety-nine percent of the counties in the United States have experienced a flood loss, so folks across the nation underappreciate the flood risk that they face. They want to think it's not going to happen to them."

Whether you bought your home or rent one, you can find your home's flood risk at floodfactor.com, a tool developed by First Street Foundation. Lopes said you don't want to see anything above a 3 out of 10.

"You're starting to get into some pretty severe risk of experiencing [flooding]," he said. "That doesn't mean your house is going to be leveled, right, but you're going to be experiencing some pretty heavy flooding over the next 15 or 30 years."