Flood Risk and Buying a Home in San Antonio (2026)

By Chris Dudley, San Antonio REALTOR®, Founder of Legacy Realty Group, brokered by Real Broker, LLC (TREC #731381). Updated October 27, 2026.

Central and South Texas can see heavy rain and fast-rising water, so checking flood risk belongs on every San Antonio buyer's list, even for homes that are not in a mapped floodplain. Here is how to check a home before you buy and what Texas law requires sellers to tell you.

1. Read the seller's flood disclosures

Most Texas resale sellers must give a Seller's Disclosure Notice. Its flood section asks whether the seller is aware of (Texas Property Code 5.008):

  • Present flood insurance coverage
  • Previous flooding from a reservoir breach or a controlled or emergency release of water
  • Previous water getting into a structure on the property from a natural flood
  • The property being wholly or partly in a 100-year floodplain (Zones A, V, A99, AE, AO, AH, VE or AR) or a 500-year floodplain (shaded Zone X)
  • The property being wholly or partly in a floodway, flood pool or reservoir

If you sign a contract before receiving the notice, the TREC resale contract lets you terminate within 7 days after you receive it (see option period and inspection). Brand-new homes that were never occupied are generally exempt from this notice, so ask the builder directly.

2. Check the maps yourself

The San Antonio River Authority offers two free tools (SARA):

  • Floodplain Viewer: shows whether a property is in the 1-percent annual chance floodplain (the "100-year" or base floodplain).
  • Risk Map Viewer: estimates a property's level of flood risk, including the chance of flooding over a 30-year mortgage.

The River Authority notes that about 25% of flood insurance claims come from areas with minimal flood risk, and it supports FEMA's recommendation that homeowners carry flood insurance through the National Flood Insurance Program.

3. Understand flood insurance before closing

  • Lender requirement: If the home is in the 1-percent annual chance floodplain, your lender may require flood insurance.
  • Standard homeowners policies: Ask your insurance agent what your policy covers; flood is usually a separate policy.
  • Waiting period: NFIP flood policies normally have a 30-day waiting period, but there is no wait when the policy is bought in connection with a loan closing and the application and premium are paid at or before closing (NFIP rule summary).
  • Get a quote during your option period so the cost is part of your decision, not a surprise.

4. Look closely during the inspection

  • Ask your inspector to note grading and drainage, gutters, and any signs of past water entry.
  • Drive the street during or after a heavy rain if you can, and look at low-water crossings on your daily route.
  • Ask the seller (or HOA) about drainage easements and past street flooding.

Frequently asked questions

How do I know if a San Antonio house is in a flood zone?

Check the seller's disclosure, then look the address up in the San Antonio River Authority's Floodplain Viewer, which shows whether it is in the 1-percent annual chance (100-year) floodplain. The Risk Map Viewer estimates the risk over a 30-year mortgage.

Does a Texas seller have to disclose flooding?

Yes. The Seller's Disclosure Notice under Texas Property Code 5.008 asks about flood insurance, previous flooding into the home, reservoir-related flooding, and whether the property is in a 100-year or 500-year floodplain, floodway, flood pool or reservoir.

Do I need flood insurance in San Antonio?

If the home is in the 1-percent annual chance floodplain, your lender may require it. Outside the floodplain it is optional, but the San Antonio River Authority notes about 25% of flood insurance claims come from minimal-risk areas.

Is there a waiting period for flood insurance when I buy a home?

NFIP policies normally take 30 days to start, but when the policy is bought with a loan closing and paid at or before closing, coverage starts at closing.

Who can help me check flood risk on San Antonio homes?

Chris Dudley is a San Antonio REALTOR® and Founder of Legacy Realty Group, brokered by Real Broker, LLC (TREC #731381), serving buyers across San Antonio, Boerne, New Braunfels, Canyon Lake, Cibolo and Schertz. Call (210) 838-6099.

Next step

Want a second set of eyes on a home's flood risk? Call or text Chris Dudley at (210) 838-6099 (Mon-Sat, 9 AM-6 PM).

Related guides: Option period and inspection | First-time buyer guide | Closing costs | Canyon Lake | New Braunfels | Boerne | FAQ

General information, not insurance or legal advice. Confirm flood zones and coverage with official maps, your lender and a licensed insurance agent.