What every consumer needs to know about flood insurance in the wake of Hurricane Harvey

— -- Eight in 10 homeowners who have already endured Harvey’s wrath may be in for another hit after the floodwaters drain and they realize their insurance won’t cover their claims, insurance experts say.

Only 15 to 20 percent of homeowners in Houston and Corpus Christi, Texas, are insured for flooding, according to a state insurance group.

The rest of the flood victims will be out of luck — and many homeowners with large mortgages might simply abandon their homes, as happened after Hurricane Katrina in New Orleans, says Robert Hunter, a former Texas insurance commissioner who is now the director of insurance for the Consumer Federation of America.

Hunter cited three big misconceptions consumers have about flood insurance:

Homeowners must purchase flood insurance if they’re in a high-risk flood zone and have a federally insured mortgage. But after a catastrophic storm like Harvey, it’s instantly clear why flood insurance is crucial even for lower-risk properties.

Gulf Coast residents struggle to recover after Hurricane Harvey

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Members of First Baptist Church of Loeb chain saw pews and clean up the church on U.S. 69 that had eight feet of water in it due to Hurricane Harvey flooding in Lumberton, Texas, Sept. 7, 2017.

Bob Daemmrich/Polaris

Less obvious is what will happen to the National Flood Insurance Program, which was having well-publicized troubles even before Harvey hit, with a deficit of more than $25 billion.

Congress is likely to extend the program at least temporarily and provide extra money for Harvey claims. After that, lawmakers will need to decide where the program goes from here and whether private insurers who previously abandoned the market should be allowed back in.

For consumers who bought a flood policy or are claiming wind damage, it’s important to act quickly. Check out FloodSmart.gov and follow these tips from the Consumer Federation of America:

Finally, read your policy carefully to see what it does — and does not — cover. During a massive Texas flood in May 2016, Micky and George Hartz found their Magnolia neighborhood under 6 feet of water, with their home taking in some of that.

“It did just enough damage that we had to knock out walls,” Micky Hartz told ABC News after the flood, when they turned to the ABC News Fixer for help with their claim. “The water came up really fast and left really quick.”

The Hartzes had flood insurance, but the home had a detached garage that was not covered under their policy.

“It was over $85,000 just to fix our house. But the garage, because it wasn’t attached to the house, it was over $20,000 worth of damage that we had to put out for that.”