For millions of Florida homeowners, flood insurance is a necessity.

Even if the homeowner’s lender doesn’t require it, it’s probably a good idea to have it in hurricane-prone Florida. But thanks to changes underway in Washington, flood insurance premiums are on track to double over the next four years.

That’s because of a bill just passed by Congress is aimed at shoring up part of the federal flood insurance program’s $18 billion debt – a debt that’s only growing in the aftermath of Tropical Storm Debby. President Barack Obama signed the bill into law as part of the Moving Ahead for Progress in the 21st Century Act on Friday.

The timing couldn’t be worse for Floridians who were hit hard by Debby.

Take Brenda Stallard and Kenneth Shurlknight. The storm inundated their home with two-story high flood waters from the Sopchoppy River.

Like a lot of people in Sopchoppy, a rural town in the shadow of Tallahassee, the Knights carry flood insurance. But they never thought they’d need it.

“We’re far enough inland that we weren’t worried about storm surge and stuff like that,” Shurlknight said. “But people we run into, we keep reminding them: ‘Hey, think about Sopchoppy,’ because it’s almost forgotten about.”

The calamity that struck the town was so devastating, clean-up could take months.

Flood insurance will pick up much of the bill. But even after everything is taken care of, many folks may still have no choice but to pick up and leave.

Brenda and Kenneth could see their premium jump all the way to $4,000 a year. They say they wouldn’t be able to keep living in Sopchoppy. But they may not be able to sell, either.

“The simple decision to raise insurance premiums is going to have a far-reaching impact, because not only will it price people out of living in areas like Sopchoppy, but those that own houses are going to find it more difficult to sell them.

And that may hold back Florida’s already struggling real estate market.

The congressional bill would raise the cap on rate increases from the current 10 to 20 percent a year. Owners of vacation homes could see the cap on their rate hikes climb to 25 percent.