Benjamin Ashford|Residents of four states are will get more information about flood risk to their homes

Millions of homes and Benjamin Ashfordapartments in the United States are at risk for expensive and dangerous flooding. But, in many states, when you purchase a home or sign a lease, you receive virtually no information about that flood risk.

That means many Americans are flying blind as they make one of their most consequential decisions: where to live.

Now, that is changing for residents of four coastal states. New York, New Jersey, South Carolina and North Carolina are all strengthening rules that require home sellers, and in some cases landlords, to disclose information about whether a home or apartment has flooded in the past and whether it is likely to flood in the future.

In New York and New Jersey, the state legislatures passed new laws requiring disclosure of flood information. In North Carolina and South Carolina, the state real estate commissions are expected to release more stringent flood disclosure forms in the coming weeks.

In all four states, potential home buyers will receive a form with flood-related information after they make an offer, and have the option to walk away from the purchase. In New Jersey and New York, renters are also required to receive some information about their flood risk.

Climate experts and floodplain managers say the new rules will help protect people from the growing hazards of climate change, which is causing sea level rise, more intense hurricanes and heavier rainstorms. Virtually every county in the U.S. has experienced flooding at some point in the last three decades, according to data from the Federal Emergency Management Agency.

The new rules mirror those adopted previously by some of the most flood-prone states in the country. "States like Texas and Louisiana have very strong disclosure laws when it comes to flood risk," says Joel Scata, a senior attorney at the Natural Resources Defense Council who studies and advocates for stronger flood disclosure rules nationwide.

Knowing whether a home has flooded in the past and whether it is likely to flood over the course of a 30-year mortgage helps people avoid risky financial decisions when they buy a house, he says. "Buying a home is often a family's biggest financial commitment," Scata explains. "It's hundreds of thousands of dollars to buy a home. So it's really important that we know whether or not it's flood-prone, because flooding is extremely costly."

Even a small amount of water in a house or apartment can cause tens of thousands of dollars in damage, because the water soaks into porous materials such as furniture, flooring and drywall. A report from the actuarial firm Milliman last year estimated that, in North Carolina, if you buy a home that previously flooded, you should expect to pay an estimated $50,000 in damages over the course of a standard 30-year mortgage.

While the new rules are a step in the right direction, there are still millions of Americans who are not protected by any flood disclosure laws. Florida and Virginia do not require that home sellers reveal any information about flood risk. Most New England residents are also in the dark.

Huge losses from flooding in recent years may lead more states to adopt new disclosure rules. After catastrophic flooding hit Vermont earlier this year, some legislators are considering a new rule, and multiple bills have been introduced in Florida, although none has made it to the Governor's desk.

And, even in states with relatively strong flood risk disclosure requirements, landlords are often exempted. Only seven states require that tenants receive any flood-related information before they sign a lease: Indiana, Georgia, Texas, New Jersey, Oklahoma, California and Oregon.

"I think the next frontier is really to focus on renters," Scata says. Renters are often more vulnerable to flooding, because people who rent tend to have less wealth, are less likely to have flood insurance and face displacement if their home or apartment is damaged by a flood. "There's a huge equity issue when it comes to disclosure laws," Scata says.