The head of the National Flood Insurance Program said Wednesday early estimates show Hurricane Harvey will result in about $11 billion in payouts to insured homeowners, mostly in southeast Texas.

That would likely put Harvey as the second costliest storm in the history of the federal insurance program, said Roy E. Wright, the Federal Emergency Management Agency’s deputy associate administrator for insurance and mitigation. More than $16 billion was paid out after Hurricane Katrina in 2005.

It is still too soon to estimate losses from Hurricane Irma, Wright said. But he predicted that the storm damage in Florida and other affected states could rival the nearly $9 billion paid out after Superstorm Sandy in 2012.

Even before the recent back-to-back hurricanes, the federal flood insurance program was about $25 billion in debt to the U.S. Treasury. Wright said the program currently has enough cash to absorb the initial wave of payments to help homeowners get back on their feet but will need billions more within about a month.

“Congress has never turned their back on a flood insurance holder, and I cannot imagine them looking away now,” Wright said. “I am confident there will be no break in the flow of funds.”

The Associated Press reported earlier this month that the total number of federal flood insurance policies nationally dropped by about 10 percent over the last 5 years, to about 4.9 million. The drop came after Congress required a premium hike in 2012 and about a half million homeowners elected to drop their coverage.

As a result, scores of homes flooded by Harvey and Irma will not be covered by federal flood insurance. Those uninsured homeowners will likely have to seek grants and loans to rebuild. Wright said such federal emergency help should be seen as a life vest, but not the full protection offered by flood insurance.

Wright said that nationally there are about 10 million residential structures, twice the number of properties currently covered, in areas that could potentially flood. That includes many homes that are outside 1-in-100 year flood plains or that don’t have federally-backed mortgages requiring flood insurance policies.

Wright said uninsured homeowners around the country should learn from what is happening in Houston and other flood-ravaged parts of the country and seriously weigh whether they should buy a policy.

“Collectively, we need more people covered,” Wright said. “We have to get beyond this conversation about what I have to do and what I’m mandated to do, and put folks in an educated position by which they are making a back-pocket economic decision.”

Wright said that under current law, FEMA is not allowed to cancel policies covering waterfront or low-lying homes that have been flooded and rebuilt multiple times. In the wake of Harvey and Irma, he said the flood insurance program will likely be refining its policies to allow the owners of such multiple-loss homes to be bought out and moved to higher ground.