Water Quality: San Marcos, TX
5 water systems • 137,288 people served
Multiple Health ViolationsWater Quality Summary
San Marcos is served by 5 public water systems with a combined service population of 137,288 people, and has 313 EPA Safe Drinking Water Act violations on record. Critically, 96 of those are health-based violations, meaning one or more contaminants were detected above EPA-established safe levels — a serious public health concern. San Marcos's violation count is 47% above the national average for Texas. Contaminants associated with violations include Bromate, Disinfection Byproducts, Fecal Coliform, TTHM, Total Haloacetic Acids (HAA5).
Contaminants Found
Probable human carcinogen that increases the risk of kidney and thyroid cancers.
Common source: Ozonation of bromide-containing water; used as flour improver
EPA limit: 0.010 mg/L (10 ppb)
Broad category of chemicals formed during disinfection, associated with increased cancer risk and adverse reproductive effects.
Common source: Reaction of disinfectants (chlorine, ozone, chloramines) with organic matter
Indicates direct fecal contamination; associated with diarrhea, cramps, nausea, and potential severe illness.
Common source: Human and animal fecal waste
EPA limit: Zero tolerance (any positive triggers violations)
Total trihalomethanes are linked to increased risk of bladder cancer and adverse reproductive outcomes.
Common source: Reaction of chlorine disinfectants with naturally occurring organic matter in water
EPA limit: 0.080 mg/L (80 ppb)
Haloacetic acids are associated with increased cancer risk and potential reproductive and developmental effects.
Common source: Reaction of chlorine disinfectants with organic matter in treated water
EPA limit: 0.060 mg/L (60 ppb)
Water Systems Serving San Marcos
| System Name | PWSID | Source | Population | Violations |
|---|---|---|---|---|
| CITY OF SAN MARCOS | TX1050001 | Surface Water | 72,970 | 10 |
| TEXAS STATE UNIVERSITY - SAN MARCOS | TX1050003 | Groundwater | 43,552 | 16 |
| CRYSTAL CLEAR SUD | TX0940015 | Surface Water | 20,766 | 287 |
| ALLIANCE REGIONAL WATER AUTHORITY 1B | TX0280027 | Groundwater | 0 | 0 |
| ALLIANCE REGIONAL WATER AUTHORITY | TX1050197 | Surface Water | 0 | 0 |
Concerned About Your Water?
A home water filter can remove common contaminants. NSF-certified filters are tested against EPA standards.
Consider a reverse osmosis system for comprehensive filtration or a carbon filter for basic improvement.
Other Cities in Texas
Data Sources
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). Data includes all recorded violations for active community water systems.