Flood Zones in the Bay Area: What to Be Careful of When Shopping for Real Estate

Deniz Kahramaner
Deniz Kahramaner
Nov 15, 2022
As a homeowner, various things are considered when buying, such as how many bedrooms, the location, the school district, and insurance premiums, to name a few. However, more needs to be considered, specifically with natural disasters — many of which aren’t typical for the California homeowner, such as a super flood.
A recent scientific study stated that the probability of a super flood in California has doubled due to increasing and worsening climate change. This new information not only calls into question the growing need for efforts against climate change but also the effects that climate change and our evolving environment might have on the probability of other natural disasters.
This article will address what a super flood is, and key data points vital to navigating real estate in California.

What is a Super Flood?

The study above claimed that the probability of a superflood in California had doubled. A superflood is a much larger, more intense flood caused by significant amounts of rainfall in a particular storm sequence.
This study was conducted by Xingying Huang of the National Center for Atmospheric Research and Daniel L. Swain of the Institute of the Environment and Sustainability, University of California, Los Angeles. These researchers found that:
  • The Community Earth System Model Large Ensemble data found that climate change “doubled the likelihood of an event capable of producing catastrophic flooding,” with future increases imminent.
  • In the future extreme storm scenario, runoff is 200 to 400% greater than the historical values in the Sierra Nevada because of increased precipitation rates and decreased snow fraction.
The nature of these findings not only affects management policies and procedures for flood and emergency services but also impacts climate adaptation and hazard mitigation.

Why Should I Care and How Does This Affect Me?

So now you might be thinking to yourself: if it is still improbable (just more likely than before), why, as a homeowner, buyer, or seller, should you care about the recent reports of super floods and storm cycles?
Doesn’t California need the water? California needs water after suffering from droughts from 2011–2018 and from 2020–2021. However, it is essential to remember that a flood can damage power, telephone, and cable lines and contaminate groundwater and tap water. Additionally, floods can cause structural damage to an area, making traveling on bridges and roadways impossible.

More Frequent Floods

California is no stranger to floods, but it has been many years since the last major flood. Though a flood is unlikely during a drought season, there could be more coming than expected.
With the increased probability of longer storm cycles due to climate change, we could potentially see the following:
  • More frequent regular floods.
  • Prolonged storm series capable of producing very large precipitation accumulations.
Hydrologic engineers can estimate the likelihood of annual flood flows and stages that could occur. This information can be used to estimate the average damage. It is best to remain informed about what could happen, especially if you live in a flood-prone area.
The California Department of Water Resources notifies property owners of their flood risks every September. And provides great other resources here.


Damage from a flood typically is not covered by a standard homeowners insurance policy — or condo or renters insurance, either. However, a separate flood insurance policy can help you get your desired coverage. It is good to note that flood insurance isn’t required for homeowners in California. According to Value Penguin, “the average cost of a National Flood Insurance Program (NFIP) policy in California is $779 per year…” but lower rates and higher coverage limits can be found through private flood insurance companies.
Flood insurance coverage comes in two categories:
  1. Building coverage helps pay for damage to the physical structure of your home — the building, the plumbing, the electrical system, heating and cooling, appliances, and things that are permanently installed, such as carpeting, bookshelves, and kitchen cabinets. Services like debris removal may also be included.
  2. Contents coverage can help you replace your belongings — furniture, smaller appliances, computers, clothing — and provide limited coverage for items such as antiques and artwork. Unless you have contents coverage, your flood-damaged belongings are not covered.
These two types of flood insurance coverage are purchased separately within your policy and will have separate deductibles.
The reality is flood insurance in high-probability zones will likely either:
  • Become more expensive
  • Become entirely unavailable
Proper flood insurance should be prioritized for homeowners in flood zones to protect themselves.
We advise our clients to speak with an insurance broker on how much flood insurance could cost and how likely coverage could be dropped. The insurance landscape is rapidly changing, and weighing the costs and benefits of living in these zones is crucial. A flood zone can easily affect the valuation of your property.

What can I do to be prepared?

One of the best things you can do to be prepared in the event of a flood or super flood is to stay informed. There are also various resources available to help you. Each of these resources will help you understand what to do in the event of a flood and how to prepare for it before it happens:


Understanding what homes in what areas are more susceptible to flooding than others is critical when beginning the buying process. Even as a seller, knowing what hazards your home may exist in or need preparation for can be a useful tool when getting ready to list and sell. In either process, existing documentation and information can be difficult to sift through. Atlasa Real Estate comes into this process with expertise and an open mind, ready to provide explanations and a helping hand to our clients.
At Atlasa, we not only pay attention to important documents during the sale and purchase that might address concerns of natural hazards but also have an extensive network that we can connect our clients with in terms of insurance and home preparation. To speak with an Atlasa agent today, please contact us at deniz@atlasa.com or check out our website at www.atlasa.com.
Real Estate
San Francisco Bay Area
Flood Insurance
Home Buying

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Deniz Kahramaner
Deniz Kahramaner is the Founder & CEO of the data-driven Real Estate Brokerage Atlasa. His mission is to help home buyers understand the tradeoffs of different home options using big data and analytics. Feel free to contact Deniz if you need help with the home buying or selling process at deniz@atlasa.com.