Across the United States, flooding is the No. 1 natural disaster, according to the Federal Emergency Management Agency. And given the region’s swollen rivers and the promise of heavy runoff this spring from melting snow, now is a good time to assess how well you’re protected against flooding.

A basic homeowner’s or business’ insurance policy will cover damage caused by storms, such as a leaky roof, fallen tree limbs or broken pipes.

But a homeowner’s policy typically does not cover damage due to flooding, or what’s known as “rising water.”

Flooding—such as  a river overflowing its banks or water from springtime snow melt—is generally defined as a temporary inundation of normally dry land. For that type of coverage, you need a separate flood policy, which is provided by the federal government’s National Flood Insurance Program and purchased through a local insurance agent. Homeowner’s insurance covers water falling from the sky; flood insurance covers water rising from the ground.

Flood insurance covers most damage to your home, business and personal property caused by temporary inundation of water. It includes mudflows, but not landslides.

One limitation to flood insurance is basements. Improvements such as walls made with dry wall, finished floors and personal belongings in a basement are not covered by flood insurance; essential household equipment such as furnaces or water heaters is covered.

For residential policies, the maximum coverage is $250,000 for the structure and $100,000 in personal property. For a business or commercial property, the maximum limits are $500,000 structural and $500,000 in contents.

Flood insurance premiums vary, depending on where you live and whether your home is considered at high or low risk of flooding.

The average residential flood insurance premium is about $570 per year, according to the NFIP. But homeowners in low-risk areas can purchase coverage for as little as $129 a year; those whose homes are in heavily flood-prone areas will pay $2,700 or more in annual premiums. Commercial property rates are higher. And keep in mind: If you get a policy today, it does not go into effect until 30 days after it’s purchased.

A quick way to check for your property’s flood risk is to visit www.floodsmart.gov. Enter your address, city, state, zip code, and specify Residential status. Your property flood risk will be displayed as well as an estimate of Flood Insurance premium costs.

In the wake of Katrina many homes that were not considered a flood risk have been reclassified by FEMA. Take a minute to check out your property.