Many people are surprised to discover that their standard homeowner’s insurance policy does not cover them in the event of a flood.

If you want flood insurance, you generally have to buy a separate policy. Typically these policies are sold by private insurers, but are backed by the U.S. Government through the National Flood Insurance Program.

Some federally backed mortgage programs require homeowners to buy flood insurance if they live in a high-risk area. Some private lenders require this as well, and they may require it even if the property is not in a high-risk area.

You should note that just because a property is not in a high-risk area doesn’t mean that flooding is impossible. High-risk areas are typically low-lying regions that are subject to storm surges or overflowing rivers, but even property in a very low-risk area can still be flooded due to heavy rainfall, drainage system failures, or a broken water main.

In fact, about 27% of all insurance claims for flooding are brought by property owners who don’t live in flood zones.

Some people mistakenly believe that if there’s a flood, their losses will be covered through a federal disaster relief program. That’s not true. You generally won’t get any assistance at all unless the government declares a disaster area, and even then, most government assistance is in the form of low-interest loans, not compensation for losses. You will eventually have to pay back these loans.

The good news is that homeowner’s policies often (though not always) cover some other types of water issues, including leaky roofs, plumbing problems, theft or fire triggered by flood damage, and frozen groundwater. On the other hand, such policies typically won’t cover sewer back-up, sump-pump failures, or leaking swimming pools, at least without a special endorsement that costs extra.

As always, it’s a good idea to review your insurance coverage regularly and make sure that you’re adequately covered.