Head-to-head water quality
Austin, TX vs San Antonio, TX
Side-by-side water quality comparison: Austin (Grade F) vs San Antonio (Grade F). Lead, PFAS, violations, and source-water contamination
Score breakdown
Each factor is shown as raw points (out of the maximum). Higher = better.
Factor
Austin
San Antonio
Better
Violations subscore / 45
0.0
0.0
Tie
Lead/Copper subscore / 20
16.0
16.0
Tie
Contaminant subscore / 20
6.2
10.1
San Antonio
Compliance subscore / 10
5.0
3.0
Austin
Source subscore / 5
4.0
4.0
Tie
Lead & copper at the tap
Lead and Copper Rule (LCR) 90th-percentile readings — the value that 10% of sampled homes exceed.
Factor
Austin
San Antonio
Better
Lead 90th-percentile (latest) · EPA action level: 15 µg/L
0.0 µg/L
0.0 µg/L
Austin
Copper 90th-percentile (latest) · EPA action level: 1.3 mg/L
2.4 mg/L
1.5 mg/L
San Antonio
PFAS — "forever chemicals"
UCMR 5 testing, 2023–2025. Federal MCLs: PFOA + PFOS = 4 ng/L; HFPO-DA = 10 ng/L.
Factor
Austin
San Antonio
Better
PFAS analytes detected
10 of 30
4 of 30
San Antonio
PFAS exceeds federal MCL
Yes
No
San Antonio
PFAS hazard index · Sum of (max/MCL) across detected analytes; > 1 indicates exceedance
1.88
—
Austin
Violation history
SDWA enforcement actions — fewer is better.
Factor
Austin
San Antonio
Better
Violations (last 5 years)
2,254
86
San Antonio
Health-based violations (total)
1,288
25
San Antonio
Unresolved violations
2,515
212
San Antonio
Other contaminants tested
UCMR rounds 1–4 + UCMR 5 lithium. Maxima where data exists; "—" means not tested.
Factor
Austin
San Antonio
Better
Chromium-6 (max)
4.01 µg/L
1.80 µg/L
San Antonio
HAA5 (avg)
11.12 µg/L
3.96 µg/L
San Antonio
Manganese (max)
72.00 µg/L
6.40 µg/L
San Antonio
Strontium (max)
2020.00 µg/L
9800.00 µg/L
Austin
1,4-Dioxane (max)
—
0.58 µg/L
San Antonio
NDMA (max)
48.04 ng/L
—
Austin
Vanadium (max)
5.25 µg/L
33.00 µg/L
Austin
Chlorate (max)
4510.00 µg/L
64.00 µg/L
San Antonio
Molybdenum (max)
59.40 µg/L
9.20 µg/L
San Antonio
Industrial proximity
Superfund National Priorities List + Toxic Release Inventory facilities within 10 miles of the city centroid.
Factor
Austin
San Antonio
Better
Superfund sites within 10 mi
0
2
Austin
TRI lbs to surface water within 10 mi (2023)
16
251
Austin
System size & source
Factor
Austin
San Antonio
Population served
1.8M
2.2M
—
Water source
Surface water
Purchased surface water
—
Number of water systems
621
18
—
See the full reports
Frequently asked
Which has better water — Austin or San Antonio?
San Antonio, TX scores higher (33.1 vs 31.2) on WaterVerge's 100-point methodology, earning a Grade F compared to Austin's Grade F. The score combines violation history, lead and copper levels, contaminant testing, monitoring compliance, and source-water type.
How is the WaterVerge water quality score calculated?
The grade combines five subscores: violation history (45 pts, weighted by recency and health-based severity), lead/copper 90th-percentile vs EPA action levels (20 pts), contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, and Superfund/TRI proximity (20 pts), monitoring compliance (10 pts), and water-source-type risk (5 pts). Full methodology at /about/methodology.
Where does this water quality data come from?
From the EPA's public records: the SDWIS bulk download (violations + system info), UCMR rounds 1–5 (unregulated contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, vanadium, lithium), the EPA Toxic Release Inventory (industrial polluters), the Superfund National Priorities List, the USGS Powell Domestic-Well Database (private-well chemistry), and the CDC Community Water Fluoridation system. Data is refreshed quarterly.