Homeowners insurance doesn't cover flooding — here are the best flood insurance companies that will

Standard homeowners insurance policies don't cover flood damage on their own, meaning that homeowners will need to look elsewhere to get coverage for flooding. 

While the risk of flooding varies by location, the Federal Emergency Management Agency (FEMA) estimates a one-in-four chance of flooding for homes in high-risk areas over the course of a 30-year mortgage.

Since even one inch of flood water can cause extensive damage — FEMA estimates about $25,000 worth — it could be beneficial for homeowners to get flood insurance coverage. And some mortgage lenders require flood insurance, especially for properties in flood zones.

There are two types of flood insurance to consider: 

• National Flood Insurance Program, or NFIP. Offered by FEMA, this can be a good option for some homeowners, but it may not work for everyone. Those with larger, more expensive homes or those in high-cost-of-living areas may not find enough coverage through the NFIP, since the maximum coverage limit for residential, single-family homes is $250,000. 
• Private flood insurance. Offered by insurance companies and not tied to FEMA, private flood insurance can provide higher coverage limits and more comprehensive protection, including coverage for basements.

NFIP policies have some notable exclusions, such as for personal property stored in the basement. The NFIP also doesn't offer any coverage for swimming pools. That's where a private flood insurance policy could be helpful. Private flood insurance policies could cover those who need more flood insurance than what's offered by the typical NFIP policy. 

To help narrow down your search, CNBC Select has rounded up some of the best private flood insurance companies on the market based on coverage and service (see our methodology below).

• Best overall: Neptune Flood Insurance
• Runner-up: Beyond Floods Insurance
• Best for high-value homes: Chubb Flood Insurance
• Best for customizable coverage: Aon Edge Flood Insurance

Neptune flood insurance is widely available and offers relatively high coverage limits out of the companies we reviewed, making it useful for people who need more coverage than the typical NFIP policy. Optional coverage for swimming pool repair and refill and unattached structures could be useful features for properties with these amenities. For homeowners with basements, basement contents coverage could be a helpful additional coverage.

Beyond Floods offers coverage through National General Insurance Company, which is an Allstate company. While this company only offers up to $1.5 million in dwelling coverage, it's a solid amount of coverage for the typical American home, and its $750,000 in contents coverage is more than some other companies we reviewed. Beyond Floods offers coverage for basements and contents and pool clean-up and repair. The only major drawback is that Beyond Floods coverage isn't available in all states.

Chubb is known for being one of the best homeowners insurance companies for covering high-value assets, and its flood insurance policies are no exception. Chubb offers up to $15 million in total flood insurance coverage (including your home's structure and contents). This limit is significantly higher than what most insurers offer, making it ideal for homeowners with expensive properties, including those in high-cost-of-living areas. Chubb caters its policies to fit the unique needs of these properties, offers automatic coverage for basement items and high coverage limits for things like art and collectibles. Chubb is also rated highly for financial strength by AM Best.

Aon Edge is available in all states except Alaska, DC, Hawaii, and Kentucky. It offers a generous amount of flood insurance coverage across two products — EZ Flood (up to $1.25 million of building coverage and $875,000 in contents coverage) and Excess Flood (up to $5 million of building and contents coverage beyond NFIP policy and EZ Flood limits).

When you purchase flood insurance, you may be asked to choose between Replacement Cost Value (RCV) coverage or Actual Cash Value (ACV) coverage. RCV coverage includes the full cost of replacing your damaged property without deducting depreciation, whereas ACV only covers the depreciated cost of your property.

Most basic flood insurance policies only provide ACV coverage. So for the most extensive flood insurance coverage, you'll want to opt for RCV coverage, which is generally offered at a premium or as an add-on.

• Are floods covered under most homeowners insurance policies?
• Who provides the most flood insurance?
• What are the disadvantages of private flood insurance?
• How do I find flood insurance?

Floods are not covered under most homeowners insurance policies. You'll need to purchase a separate flood insurance policy if you want to cover your home and its contents from flood damage, through either the NFIP or a private flood insurance carrier. 

The National Flood Insurance Program (NFIP) provides much of the U.S.'s flood insurance coverage — about 5 million flood insurance policies are managed through FEMA's program. This federal flood insurance is generally sold through companies that participate in the NFIP's write-your-own program, including many companies you may already have a relationship with. For many people, NFIP coverage is a strong option. 

However, NFIP coverage doesn't work for every home or situation. The coverage limits are capped at $250,000 for residences, with contents coverage limited to $100,000. For people with properties in areas where real estate values are high or those with higher-value homes, the NFIP's coverage limit may not be sufficient. Additionally, NFIP coverage excludes coverage for swimming pools and limits coverage for basement improvements and personal belongings kept in a basement. 

Private flood insurance can offer higher limits of coverage, and it can also provide additional coverage for situations and items that NFIP policies do not include. 

Private flood insurance companies can be a good option for those who need more coverage than the NFIP can offer. However, it can also come with disadvantages, including the fact that a private insurer can not renew your flood insurance or cancel your policy at their discretion. 

While this isn't a problem with NFIP coverage, the limited coverage through the federal program may not be enough for every property. 

To find flood insurance, you'll need to figure out how much coverage you need. There are a few ways to determine how much you need: 

• Find out how much is required for your mortgage. The amount of flood insurance coverage required by your mortgage lender varies by the type of mortgage loan you have. Not all mortgages require flood insurance. 
• Determine your home's replacement cost value. If your mortgage doesn't require flood insurance, it's still possible to get it and estimate how much you need. An appraisal or your insurance company can help you find the replacement cost of your home. This number is different from the market value of your home.

Once you have a number in mind, you'll want to decide whether you want to get private flood insurance, NFIP insurance, or a combination of the two. Some insurance companies, including Aon Edge, offer excess flood insurance policies to build onto the coverage of an NFIP policy. To qualify for an NFIP policy, you'll need to live in one of the 22,600 communities that participate in the program. 

To get NFIP coverage, you'll need to contact an insurance agent that sells the coverage or one of the companies that participate in the program to get a quote on your own. Similarly for private flood insurance, you'll want to contact an agent or flood insurance company and gather quotes.

To find the best coverage for the money for either type of coverage, you'll want to get several quotes and compare them. Look at the types of coverage offered, what each type of coverage would include and the deductible, or the amount you'll pay out of pocket before your flood insurance kicks in. Then, consider the price you'll pay for coverage, called a premium.

Since flooding isn't covered under many homeowners insurance policies, getting a separate flood insurance policy may make sense. This coverage can come from either a private flood insurance company or the NFIP depending on your property's value and unique features.

At CNBC Select, our mission is to provide our readers with high-quality service journalism and comprehensive consumer advice so they can make informed decisions with their money. Every flood insurance review is based on rigorous reporting by our team of expert writers and editors with extensive knowledge of insurance products. While CNBC Select earns a commission from affiliate partners on many offers and links, we create all our content without input from our commercial team or any outside third parties, and we pride ourselves on our journalistic standards and ethics. See our methodology for more information on how we choose the best flood insurance.

To determine the best flood insurance companies, CNBC Select looked at many U.S. insurance companies that offer flood insurance, focusing on their private flood insurance coverage.

When narrowing down and ranking the best flood insurance companies, we focused on the available coverage types, geographic availability by state, coverage limits for dwellings/structures and coverage limits for contents and financial strength ratings from AM Best.

After reviewing the above features, we sorted our recommendations by best overall, runner-up, best for high-value homes and best for customizable coverage.

Note that the policy structures advertised for flood insurance companies are subject to fluctuate in accordance with the company's policies.

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