- EPA's UCMR 5 testing looked for 30 contaminants here and found 4.
- Lithium: found in 5 of 26 samples, average 2.02 µg/L, highest 11.3 µg/L (EPA UCMR 5 testing, Nov 2023–Aug 2024)
Public EPA test results
What EPA records show for City of San Marcos
EPA TX1050001 · serves Hays County, TX · about 72,970 people (EPA SDWIS)
This report shows EPA's federal records for this water system: UCMR 5 testing, lead testing and violations. It isn't a test of the water at your tap, and it has no Water Score.
Public EPA test results
City of San Marcos (EPA TX1050001)
What EPA records show for City of San Marcos, as of October 14, 2026
Health-based violation: Stage 2 Disinfectants and Disinfection Byproducts Rule, TTHM, Oct 2025–Jan 2026 (EPA SDWIS).
Lead, 90th percentile: 1.63 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2022–Dec 31, 2024). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 4.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does City of San Marcos use chloramine?
EPA treatment records (state-reported) list chloramines for City of San Marcos. EPA record
What EPA records show for this system
Reported results in EPA records (data as of Oct 14–15, 2026)