C43/100
San Marcos Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 137,288 residents · Texas
What's In San Marcos's Tap Water?
69
Contaminants Tested
0
Exceed EPA Limits
2
Above EPA Goals
2 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
chlorate | 220.00 µg/L | — | Above Goal |
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2021.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
CRYSTAL CLEAR SUD
Population Served
20,766
Water Source
Purchased Surface Water
System ID
TX0940015
CITY OF SAN MARCOS
Population Served
72,970
Water Source
Surface Water
System ID
TX1050001
TEXAS STATE UNIVERSITY - SAN MARCOS
Population Served
43,552
Water Source
Groundwater
System ID
TX1050003
Frequently Asked Questions About San Marcos Water
Is San Marcos tap water safe to drink?
San Marcos, Texas tap water receives a grade of C (43/100), which is considered fair. 1 contaminant(s) exceed EPA maximum contaminant levels and 165 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.
What contaminants are in San Marcos's water?
Of the 70 contaminants tested in San Marcos's water supply, the most notable include Copper (90th percentile), Lead (90th percentile), chlorate. 1 contaminant(s) exceed EPA legal limits (MCLs). 3 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does San Marcos have any water quality violations?
Yes, San Marcos has 165 EPA violation(s) on record, with the most recent in 2021. Violation types include MR, MCL, Other. 55 of these are health-based violations, which are the most serious category.
Do I need a water filter in San Marcos?
Based on EPA data, using a water filter in San Marcos is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does San Marcos's tap water come from?
San Marcos's drinking water is sourced from purchased surface water and supplied by CRYSTAL CLEAR SUD and 2 other water system(s). The system serves approximately 137,288 people. Surface water sources include rivers, lakes, and reservoirs.
How often is San Marcos's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. San Marcos's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does San Marcos's water compare to other cities in Texas?
San Marcos's water quality score of 43/100 earns a grade of C, which is considered fair. This is a below-average score that indicates room for improvement. Visit our Texas state page to see how all cities in the state compare.
What should I do if I'm concerned about San Marcos's water quality?
If you have concerns about San Marcos's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (CRYSTAL CLEAR SUD) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.