City of San Marcos
EPA ID: TX1050001 · 72,970 people served · 8 ZIP codes
A total of 1 EPA violation spanning the past five monitoring years sit on City of San Marcos's record — every finding has been officially cleared, and the supplier now holds current compliance status for its service population of approximately 72,970 people, with no outstanding enforcement of any kind.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Worsening · Risk tier: High · 95% chance of violation in next 12 months
Violations went from 12 (2022) to 22 (2025). The pattern suggests growing compliance challenges.
Service Area Map
Coverage area for City of San Marcos Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The City of San Marcos serves a community with a median household income of $84,426 and an estimated 284,454 residents across its service area.
Environmental Justice Note: 34% of the population in this service area is classified as disadvantaged under EPA's EJScreen criteria. Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
City of San Marcos's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in Comal County, Texas rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How City of San Marcos compares to EPA limits
What This Means For You
Contaminant 1009 at 1 mg/L exceeds the EPA maximum of 0.004 mg/L. Intestinal damage, bone damage. Consider reverse osmosis filtration.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 23 detections recorded. 2 exceed federal EPA limits (4 ppt for PFOA/PFOS).
Contaminant 1009 was detected in this water system. reverse osmosis filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
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Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
CITY OF SAN MARCOS (EPA ID: TX1050001) is a community water system in Texas that serves approximately 72,970 people from surface water sources.
This system provides water to 8 ZIP codes across 7 communities.
Average Home Safety Score: B (83/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Contaminant 1009 | Other Violation | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 6 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 2 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 78130 — New Braunfels
- 78619 — Driftwood
- 78640 — Kyle
- 78655 — Martindale
- 78656 — Maxwell
- 78666 — San Marcos
- 78667 — San Marcos
- 78676 — Wimberley
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of San Marcos (TX1050001) on EPA.gov.
Frequently Asked Questions
Is City of San Marcos water safe to drink?
City of San Marcos has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does City of San Marcos serve?
City of San Marcos serves approximately 72,970 people across 8 ZIP codes in Texas.
Where does City of San Marcos get its water?
The primary water source is surface water.
Contact Your Water Utility
Public-record contact information for the water utility serving this system. Use these channels to request water quality reports, ask about service, or report issues directly.
Contact information from CITY OF SAN MARCOS, TEXAS Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility, does not act as its agent, and does not provide customer support for it. Contact details shown are public-record information from CCR filings. For service issues, contact the utility directly using the information above.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: CITY OF SAN MARCOS, TEXAS Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
A Source Water Susceptibility Assessment for your drinking water source(s) is in process and will be reviewed by the Texas Commission on Environmental Quality.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Treatment classification and chemical list sourced from CITY OF SAN MARCOS, TEXAS Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
PFAS Substances Detected in This System
This water system's Consumer Confidence Report disclosed the following PFAS compounds. Levels are from the utility's most recent reporting cycle.
In April 2024, EPA finalized the first National Primary Drinking Water Regulation for six PFAS. Public water systems have until 2029 to comply. EPA — PFAS regulation overview →
Source: Consumer Confidence Report disclosed by CITY OF SAN MARCOS, TEXAS.
ZipCheckup is not affiliated with this water utility. PFAS detection data is sourced from public Consumer Confidence Reports filed by the utility itself.
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Hard water detected in CITY OF SAN MARCOS, TEXAS
Your utility reported water hardness of 269 ppm CaCO₃ (16 grains per gallon) in its most recent Consumer Confidence Report. This is in the very hard range and may cause scale buildup, reduced appliance lifespan, and dry skin or hair.
There are three common approaches to treating hard water: salt-based ion-exchange softeners (most effective, require salt refills), salt-free conditioners (lower maintenance, scale prevention only), and reverse osmosis at the kitchen sink (cooking and drinking water only). Aquasana, EcoWater, Pelican, and SpringWell are among the major US brands.
Paid Partner. ZipCheckup earns commission on Aquasana purchases. We do not test water or verify product effectiveness for specific hardness levels — manufacturer claims are theirs alone. Consult a certified water-quality professional for personalized advice.
Hardness data parsed from this utility's most recent Consumer Confidence Report. Severity bands per USGS hard water classification.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
- #49 / 50 Most Unresolved Health Violations (Texas)
- #29 / 50 Highest Exposure Burden (Texas)
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of San Marcos (EPA ID: TX1050001) — request the latest Consumer Confidence Report or ask about specific contaminants.