Throughout San Antonio and across its water systems, EPA compliance data for TX shows above-average performance — violations are minimal, none of the tracked systems have recorded repeated MCL exceedances in recent cycles, and the safety picture has held steady across multiple reporting periods.

Data: EPA SDWIS Last verified: 2026-06-03

Water Quality Map: San Antonio, TX

Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.

A B C D F

Overview

We track water quality and home safety data for 86 ZIP codes in San Antonio, Texas, covering 19 community water systems serving approximately 1,860,461 people.

86 of 86 ZIP codes (100%) have recorded EPA violations. 86 health-based violations documented.

Home Safety Score

Average Home Safety Score for San Antonio: A (92/100)

The score combines three factors:

Factor	What It Measures
Water Quality	EPA violations and compliance history
Lead Levels	90th percentile lead concentration vs EPA action level
Radon Risk	EPA radon zone classification

Water Sources

San Antonio water systems draw from: Groundwater, Surface water.

Lead & Copper

• Average lead level (90th percentile): 0.0016 mg/L (EPA action level: 0.015 mg/L)
• 0 ZIP codes exceed the EPA lead action level

Radon Risk

Dominant radon zone: Zone 3 (Low Risk)

• Zone 1 (High): 0 ZIP codes
• Zone 2 (Moderate): 0 ZIP codes
• Zone 3 (Low): 86 ZIP codes

Top Contaminants

Areas with Most Violations

All ZIP Codes in San Antonio

• 78201 [B] — 2 violations ⚠
• 78202 [A] — 2 violations ⚠
• 78203 [A] — 2 violations ⚠
• 78204 [A] — 2 violations ⚠
• 78205 [A] — 2 violations ⚠
• 78206 [A] — 2 violations ⚠
• 78207 [A] — 2 violations ⚠
• 78208 [A] — 2 violations ⚠
• 78209 [B] — 2 violations ⚠
• 78210 [A] — 2 violations ⚠
• 78211 [A] — 2 violations ⚠
• 78212 [B] — 2 violations ⚠
• 78213 [B] — 2 violations ⚠
• 78214 [A] — 2 violations ⚠
• 78215 [A] — 2 violations ⚠
• 78216 [B] — 2 violations ⚠
• 78217 [B] — 2 violations ⚠
• 78218 [B] — 2 violations ⚠
• 78219 [A] — 2 violations ⚠
• 78220 [A] — 2 violations ⚠
• 78221 [A] — 2 violations ⚠
• 78222 [A] — 2 violations ⚠
• 78223 [A] — 2 violations ⚠
• 78224 [A] — 2 violations ⚠
• 78225 [A] — 2 violations ⚠
• 78226 [A] — 2 violations ⚠
• 78227 [B] — 2 violations ⚠
• 78228 [B] — 2 violations ⚠
• 78229 [A] — 2 violations ⚠
• 78230 [B] — 2 violations ⚠
• 78231 [A] — 2 violations ⚠
• 78232 [B] — 2 violations ⚠
• 78233 [A] — 2 violations ⚠
• 78234 [A] — 2 violations ⚠
• 78235 [A] — 2 violations ⚠
• 78237 [A] — 2 violations ⚠
• 78238 [B] — 2 violations ⚠
• 78239 [A] — 2 violations ⚠
• 78240 [A] — 2 violations ⚠
• 78241 [A] — 2 violations ⚠
• 78242 [A] — 2 violations ⚠
• 78243 [A] — 2 violations ⚠
• 78244 [A] — 2 violations ⚠
• 78245 [A] — 2 violations ⚠
• 78246 [A] — 2 violations ⚠
• 78247 [A] — 2 violations ⚠
• 78248 [A] — 2 violations ⚠
• 78249 [A] — 2 violations ⚠
• 78250 [A] — 2 violations ⚠
• 78251 [A] — 2 violations ⚠
• 78252 [A] — 2 violations ⚠
• 78253 [A] — 2 violations ⚠
• 78254 [A] — 2 violations ⚠
• 78255 [A] — 2 violations ⚠
• 78256 [A] — 2 violations ⚠
• 78257 [A] — 2 violations ⚠
• 78258 [A] — 2 violations ⚠
• 78259 [A] — 2 violations ⚠
• 78260 [A] — 2 violations ⚠
• 78261 [A] — 2 violations ⚠
• 78263 [A] — 2 violations ⚠
• 78264 [A] — 2 violations ⚠
• 78265 [A] — 2 violations ⚠
• 78266 [A] — 2 violations ⚠
• 78268 [A] — 2 violations ⚠
• 78269 [A] — 2 violations ⚠
• 78270 [A] — 2 violations ⚠
• 78278 [A] — 2 violations ⚠
• 78279 [A] — 2 violations ⚠
• 78280 [A] — 2 violations ⚠
• 78283 [A] — 2 violations ⚠
• 78284 [A] — 2 violations ⚠
• 78285 [A] — 2 violations ⚠
• 78286 [A] — 2 violations ⚠
• 78287 [A] — 2 violations ⚠
• 78288 [A] — 2 violations ⚠
• 78289 [A] — 2 violations ⚠
• 78291 [A] — 2 violations ⚠
• 78292 [A] — 2 violations ⚠
• 78293 [A] — 2 violations ⚠
• 78294 [A] — 2 violations ⚠
• 78295 [A] — 2 violations ⚠
• 78296 [A] — 2 violations ⚠
• 78297 [A] — 2 violations ⚠
• 78298 [A] — 2 violations ⚠
• 78299 [A] — 2 violations ⚠

Data Sources

• Water quality: EPA Safe Drinking Water Information System (SDWIS)
• Lead/copper: EPA Lead and Copper Rule sampling data
• Radon: EPA Map of Radon Zones

Updated daily.

Housing Age Profile

For a city with a median build year of 1982, San Antonio carries a housing profile that straddles the 1986 federal ban on lead solder in plumbing. Neither predominantly new nor predominantly old, the stock presents a moderate aggregate risk environment — with individual risk varying sharply depending on when and where a specific home was built.

1982

Median Year Built

49%

Pre-1986 (Lead Paint Risk)

20%

Pre-1970 (Lead Pipes Risk)

Pre-1970 (20%) 1970–1986 (29%) Post-1986 (51%)

Most homes in San Antonio were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.

Source: U.S. Census Bureau ACS B25034.

San Antonio: Remediation Cost in Perspective

Remediation costs in San Antonio are small relative to typical property values — the cost-to-value ratio here is favorable.

Median Home Value

$216,100

Est. Remediation

$1,653

Remediation as % of home value 0.8%

Remediation costs in San Antonio are relatively low compared to home values. The $1,040–$2,663 estimated range is a small fraction of median property value. Home values are 5% below the Texas average.

Protecting Children from Lead in San Antonio

49%

Homes Built Before 1986

0.0016

mg/L Avg Lead (Limit: 0.015)

Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.

Households with kids in the home — for whom CDC guidance places particular weight on minimizing exposure — face a specific local picture in San Antonio. 49% of homes here come from the pre-rule era, and aggregate utility samples either approach or cross 0.015 mg/L. A baseline draw-test kit and certified lead-removal filtration are available via retailer networks for households confirming conditions at a specific tap.

Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.

Climate-Related Water Risk for San Antonio

Across the years captured by NFIP data, San Antonio has logged 2152 flood insurance claims and carries 67% of its ZIP codes within FEMA-designated flood zones — a sustained record consistent with high flood exposure. The water quality implications run through several pathways: treatment systems repeatedly stressed by high-volume intake, private wells in FEMA zones facing recurring infiltration risk, and distribution infrastructure that has likely experienced multiple backflow episodes during large events.

2,152

Total FEMA Flood Claims

$21,274

Avg Claim Payout

67%

ZIPs in FEMA Flood Zones

~108

Est. Claims/Year

San Antonio has a significant flood history with 2,152 FEMA flood insurance claims on record, averaging $21,274 per claim. With 67% of ZIP codes in FEMA-designated flood zones, flood risk is a major concern for homeowners and water quality.

How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,653</strong> remediation cost per household.

Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.

Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.