Is there PFAS in East Rio Hondo WSC water?
Some. At least one sample reached an EPA limit, but the average at every sampling point stayed below it.
East Rio Hondo WSC
Serves 24,756 people · 12 PFOA samples from 4 sampling points · Jul 2024 to Apr 2026
One or more samples at an EPA limit
PFOA Perfluorooctanoic acid
1.4 ppt avg · max 5.4
PFOS Perfluorooctanesulfonic acid
3.8 ppt avg · max 5.6
PFHxS Perfluorohexanesulfonic acid
1.9 ppt avg · max 4.5
Hazard index GenX, PFBS, PFNA, PFHxS combined
0.2 avg · max 0.5
Also detected, no federal limit: PFBA, PFPeA, PFHxA, PFHpA, PFBS.
East Rio Hondo WSC is a public water system drawing on surface water, based in Rio Hondo, Texas, serving about 24,756 people, including Harlingen, Port Isabel, Rio Hondo, San Benito. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 12 times across 4 sampling points between Jul 2024 and Apr 2026.
Every PFAS detected
Not detected: 11Cl-PF3OUdS, PFUnA, PFDoA, PFDA, PFNA, PFMBA, ADONA, HFPO-DA, 6:2 FTS, 4:2 FTS, 8:2 FTS, PFEESA, NFDHA, PFPeS, PFHpS, PFTrDA, NEtFOSAA, NMeFOSAA, 9Cl-PF3ONS, PFTA, PFMPA.
Lithium, tested in the same program: highest 58.9 ppb, detected in 12 of 12 samples. EPA's health-based screening level is 10 ppb.
What the EPA limits mean here
In April 2024 EPA set enforceable limits of 4 ppt for PFOA and PFOS, 10 ppt each for PFHxS, PFNA and GenX, and a hazard index of 1 for mixtures. Utilities were given until 2029 to comply. In May 2026 EPA proposed keeping only the PFOA and PFOS limits and moving that deadline to 2031. Until that proposal is final, the 2024 limits stand.
Compliance is judged on a running annual average at each entry point, so we show the average at this system's worst sampling point next to its single highest result. UCMR 5 results do not by themselves put a utility in or out of compliance.
What you can do at home
Two routes work for PFAS. For drinking and cooking water only, a reverse osmosis system certified to NSF/ANSI 58 with a PFOA/PFOS reduction claim is the cheapest proven option. To treat every tap and shower, a whole-house carbon system with enough contact time works, but check that the maker has PFAS test data, not just a marketing claim. See the best filters for PFAS and how PFAS removal works.
Other systems in Texas
All 1154 tested systems in Texas
ZIP codes served
78550 78552 78578 78583 78586
As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.
Cite this page
Well & Tap. "PFAS in East Rio Hondo WSC water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID TX0310096. https://wellandtap.com/pfas/texas/east-rio-hondo-wsc/
About this data
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID TX0310096). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
