Public EPA test results
What EPA records show for Tud - Upper Basin Water System
EPA CA5510012 · serves Tuolumne County, CA · about 13,331 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
Tud - Upper Basin Water System (EPA CA5510012)
What EPA records show for Tud - Upper Basin Water System, as of October 14, 2026
We found no health-based violations in EPA's records for this system (CA5510012) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Tud - Upper Basin Water System (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 0 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, 2024–Dec 31, 2026). 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 none.
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 Tud - Upper Basin Water System use chloramine?
We didn't find chloramine in Tud - Upper Basin Water System's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.
What EPA records show for this system
Reported results in EPA records (data as of Oct 14–15, 2026)