Flood insurance is generally covered by a standalone policy.
A common misconception is that flood insurance is only available through the government; in fact, private carriers may offer coverage depending on the location. Another misconception is that flood insurance is only needed if you're in a flood zone.
Every location should have flood insurance. If you are in a flood zone and have financing, you likely will be required by the bank or financial institution to carry flood insurance. Flood insurance typically has a separate policy for each store.