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Rio WSC water quality report, rewritten

Serves
6,939
Connections
2,313
Water source
Surface water
Based in
Rio Grande City, TX
County
Starr
Owner
Local government
The ZIP code it serves

78582

PWSID TX21400162026 edition · EPA data

Read this first

  • Lithium (above EPA’s health benchmark) was found in four of 4 samples, highest 43.7 ppb. Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

1 health-based violation since 2016. Details are below.

What was found

Highlighted: above the health goal, or EPA’s health benchmark where there is no goal. Circled: above the legal limit in at least one sample, or the action level. Every scale puts that line at its middle.

43.7ppb

Highest of 4 samples; found in four

Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

What handles it

No certification claim covers this compound yet.

EPA UCMR 5, samples taken from Jan. 23, 2023 to Oct. 18, 2023. Each blue tick is one sample where it was found.

Also found, with no federal limit

EPA measured these PFAS to learn how often they occur. None has a legal limit or a health goal yet.

CompoundHighest sampleFound inCertification claim
PFBA7.7 ppt2 of 4None covers it

Tested and not found

Below EPA’s minimum reporting level in every sample taken from Jan. 23, 2023 to Jan. 31, 2024. Not found means not measured above that level, which is not the same as zero.

All 29 compounds tested and not found
  • 11Cl-PF3OUdS
  • 4:2 FTS
  • 6:2 FTS
  • 8:2 FTS
  • 9Cl-PF3ONS
  • ADONA
  • HFPO-DA (GenX)
  • Lead
  • NEtFOSAA
  • NFDHA
  • NMeFOSAA
  • PFBS
  • PFDA
  • PFDoA
  • PFEESA
  • PFHpA
  • PFHpS
  • PFHxA
  • PFHxS
  • PFMBA
  • PFMPA
  • PFNA
  • PFOA
  • PFOS
  • PFPeA
  • PFPeS
  • PFTA
  • PFTrDA
  • PFUnA

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Lead and Copper Rule RevisionsThe required inventory of lead service lines was not completed or submitted on time.EPA: LSL InventoryOct. 17, 2024—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 32 monitoring or reporting violations not shown.

What this report cannot tell you

  • Levels of everything else. Federal bulk data carries results for PFAS, lithium, lead and copper, and violations for the rest. Nitrate, arsenic, disinfection byproducts and other levels are in Rio WSC’s own annual report, which it must send you every year.
  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
  • Anything after the latest data. SDWIS data is from 2026 Q2; UCMR 5 samples are from Jan. 23, 2023 to Jan. 31, 2024.

What to do next

  1. Read up on Lithium

    What each one does to health, where it comes from, and the certification claim that addresses it.

    About Lithium

  2. Get the utility’s own report

    Rio WSC must send you a water quality report every year. It lists nitrate, arsenic and byproduct levels this page cannot.

    How to read it

  3. Test your own tap for lead

    Your service line, solder and fixtures decide the lead at your faucet, not the utility’s average.

    Lead in your water: what to do

  4. Decide if you want a filter at all

    A filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.

    NSF/ANSI standards, decoded

Other Texas utilities

All Texas utilities

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