Look up the address on FEMA’s Flood Map Service Center, then check the San Antonio River Authority’s Floodplain Viewer, which also shows draft floodplain maps still under FEMA review. If you’re buying a resale home, read Section 6 of the Texas Seller’s Disclosure, which asks about floodplains, past flooding, and flood claims. Here’s how to read the results, what changes on a new build, and when your lender will require flood insurance.
Brock Bremmer | U.S. Air Force Reserves Veteran | Real Estate Agent | eXp Realty | San Antonio Metro Area
Home Buyer Guide
Also see: First-Time Buyer Guide | The Texas Option Period | New Construction Inspections
What Do the Flood Zone Letters Mean?
FEMA’s flood maps sort land into zones. Bexar County’s floodplain office puts it plainly: everyone is in a floodplain, and the question is how much risk. These are the zones you’ll see most around Bexar County:
| Zone | What It Means |
| A, AE (and AO, AH) | High-risk Special Flood Hazard Area, the “100-year” floodplain with a 1% chance of flooding each year |
| Floodway | The channel and nearby land that carry floodwater, usually inside a Zone AE area |
| X (shaded) | Moderate risk, the “500-year” floodplain |
| X (unshaded) | Lowest mapped risk, but not zero |
A 1% yearly chance sounds small. FEMA notes it works out to about a 26% chance of flooding at least once over a 30-year mortgage.
How Do You Look Up a Specific Address?
- FEMA Flood Map Service Center (msc.fema.gov): Enter the address to see the effective flood map, the zone, and any Letters of Map Change that apply
- SARA Floodplain Viewer: The San Antonio River Authority maintains floodplain maps for Bexar County, the City of San Antonio, and 19 suburban cities as a FEMA Cooperating Technical Partner. Its viewer shows effective maps and draft floodplains under FEMA review, so you can see if a zone may change
- Bexar Flood Facts: Bexar County points residents to this tool for property-level flood risk information
- Low-water crossings: BexarFlood.org shows crossings watched by the HALT warning system. SARA says more than 190 crossings in Bexar County are monitored, which matters for your commute even if the house is high and dry
If the line runs through the lot, look at where the house sits, not just the parcel. A backyard in Zone AE with the house outside it is a different situation from a house sitting in the zone.
What Does the Texas Seller’s Disclosure Tell You?
On most resale homes, Texas Property Code Section 5.008 requires the seller’s disclosure notice. Its flood section asks whether the seller knows of:
- Insurance: Present flood insurance coverage
- Past flooding: Flooding from a reservoir release, or water getting into the home from a natural flood
- Mapped location: Whether the property is wholly or partly in a 100-year floodplain, a 500-year floodplain, a floodway, a flood pool, or a reservoir
- Claims and aid: Flood insurance claims, including through the National Flood Insurance Program, and any FEMA or Small Business Administration assistance for flood damage
The same form asks about military installation noise and air zones, which applies near JBSA-Lackland, JBSA-Randolph, and other bases. If the seller delivers the notice after the contract’s effective date, you may terminate within seven days of receiving it. Read it before you sign, and use your option period to ask follow-up questions.
What Changes If You’re Buying a New Build?
Section 5.008 exempts a new residence that has never been occupied, so a builder doesn’t hand you that disclosure. You have to ask. Here’s what I’d request:
- Plat and survey: Where the lot sits relative to any mapped floodplain or drainage easement
- Map changes: Whether the community relied on a Letter of Map Revision (LOMR), which updates FEMA maps after construction like channel or detention work
- Elevation certificate: Especially if any part of the lot is in or near a mapped zone
- Grading and drainage: How water moves off your lot and where the detention ponds are
I cover more questions to ask a builder in 5 Questions You MUST Ask Before Buying a New Construction Home in San Antonio on my YouTube channel.
Do You Have to Buy Flood Insurance?
It depends on the zone and the loan. Under federal law, a federally regulated lender can’t make a loan on a building in a Special Flood Hazard Area without flood insurance, and SARA notes that a federally backed mortgage on a floodplain property requires it. That covers most conventional, FHA, and VA buyers.
Outside the high-risk zones, it’s your choice. Bexar County itself doesn’t require flood insurance. SARA reported that as of August 31, 2022, the average National Flood Insurance Program premium plus fees in Bexar County was $783.45 a year, with average coverage of $285,505. Your quote will depend on the home.
Timing matters too. An NFIP policy normally has a 30-day waiting period, but it’s waived when you buy the policy in connection with getting a loan, as long as you apply and pay the premium at or before closing. Get the quote early so it fits into your escrow and payment budget.
What Else Affects a Home’s Flood Risk?
The zone is only a starting point. Bexar County lists other factors that matter:
- Elevation: How high the finished floor sits compared to the expected flood level
- Equipment: Where the HVAC, water heater, and electrical panel are placed
- Site grading: Whether the ground slopes water away from the foundation
Your inspector can comment on grading and drainage. Walk the street after a heavy rain if you can, and look at where water collects.
Frequently Asked Questions: San Antonio Flood Zones
Does a seller have to tell you if a house is in a flood zone in Texas?
On most resale homes, yes. The seller’s disclosure required by Texas Property Code Section 5.008 asks whether the property is in a 100-year or 500-year floodplain, a floodway, a flood pool, or a reservoir, and about past flooding and claims. New homes that have never been occupied are exempt, so ask the builder directly.
Is flood insurance required in San Antonio?
Only in some cases. If the home is in a high-risk Special Flood Hazard Area and you use a federally backed or federally regulated loan, your lender will require it. Outside those zones it’s optional, and Bexar County doesn’t require it on its own.
Ready to Buy a Home With Fewer Surprises?
Brock Bremmer with eXp Realty is a U.S. Air Force Reserves veteran who has helped buyers and sellers close 120+ homes across the San Antonio metro. He helps buyers check flood maps, disclosures, and builder documents before the option period runs out, and line up insurance quotes early.
- 📞 Call or text: 210-501-5088
- 📧 Email: [email protected]
- 📅 Schedule a free consultation
Also see: Selling Your Home in San Antonio | New Construction Financing | Buying as a VA and Military Buyer
Sources: FEMA, flood risk for homeowners; FEMA Flood Map Service Center; Bexar County, Floodplain; San Antonio River Authority, flood risk (mapping, insurance data); San Antonio River Authority, maps and Floodplain Viewer; BexarFlood.org; Texas Property Code Section 5.008; Interagency Questions and Answers Regarding Flood Insurance; 44 CFR 61.11 (NFIP waiting period).