Skip to main content
WaterSafeCheck
Official EPA SDWIS Verified ReportWater Quality & Testing GuideHistorical Record: No Recorded SDWIS Violations

ZIP Code 78570 Water Quality & Testing Report

Mercedes, TX · Hidalgo County County · Updated for 2026

Sahajul HaqueCompiled & verified by Sahajul Haque from official EPA SDWIS records
Public Health & Medical Notice: Drinking water quality data on this page reflects historical compliance records submitted under the Safe Drinking Water Act. This information does not constitute medical advice or a real-time safety guarantee. If you are pregnant, nursing, preparing infant formula, or immunocompromised, consult a healthcare provider. Boiling water kills biological pathogens, but does NOT remove chemical contaminants like lead, arsenic, or PFAS.
Quick EPA Verified Answer

Is Tap Water Safe to Drink in ZIP 78570 (Mercedes, TX)?

Caution / Filtration Recommended: Tap water in ZIP code 78570 (Mercedes, TX) has compliance concerns, earning an EPA Safety Grade of C (60/100) due to 5 health violation(s) and 3.7 ppb lead. While treated by City of Mercedes, residents are advised to use an NSF/ANSI 53 certified water filter for drinking and cooking.

Safety Score
C

Water Safety Grade

Fair — Some compliance concerns

Health Violations

5

Total Violations

55

Lead Risk

Moderate

Contaminants

2

⚠

Active Water Quality Issues Detected

EPA records show 11 unresolved violations. Contact City of Mercedes for current status.

About Tap Water in ZIP Code 78570

Tap water in ZIP code 78570 (Mercedes, TX) is distributed by City of Mercedes (EPA ID: TX1080007), serving approximately 16,258 residents. Based on EPA Safe Drinking Water Act compliance records, this system receives a water safety grade of C with a composite quality score of 60/100.

Water System

City of Mercedes

EPA ID: TX1080007

Water Source

Surface Water

Population Served

16,258 residents

County

Hidalgo County County, Texas

🧪

Lead Levels in ZIP 78570

EPA action level: 15 ppb | Public health goal: 0 ppb

Lead Level: 3.7 ppb — Very Low

The 90th percentile lead level in 78570 is 3.7 ppb. This meets the EPA action level of 15 ppb. Health experts recommend a target of 0 ppb for optimal safety.

Lead exposure risk in 78570 is rated Moderate. EPA models estimate a 36% exposure probability based on housing and infrastructure age.

Lead Level (90th percentile)
3.70 ppb (0.0037 mg/L)
Copper Level (90th percentile)

EPA action level: 1.3 mg/L

1.66 mg/L
Lead Exposure Risk Rating
Moderate
Lead Exposure Probability

EPA model estimate based on housing age and infrastructure

36%
Note: Lead levels above are the 90th percentile from EPA monitoring — meaning 90% of samples were at or below this level. Even "undetected" tap water lead doesn't account for lead leaching from home plumbing. If your home was built before 1986, individual tap testing is recommended.
🪨

Water Hardness & Mineral Content

Grains per gallon (GPG) & Parts per million (PPM / mg/L)

Classification: Very Hard10.7 GPG · 183 mg/L

Water in ZIP 78570 is Very Hard (183 mg/L / 10.7 GPG). High concentrations of dissolved limestone minerals cause severe mineral buildup, stiff laundry, dry skin, and premature water heater wear.

Recommendation: A whole-home water softener system is strongly recommended to protect plumbing and home appliances.
Hardness (GPG)

Grains per gallon

10.7 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

183 mg/L
Appliance Scaling Risk
High / Severe

Official EPA SDWIS Database Entry

Utility: City of Mercedes · PWSID: TX1080007

Verify on EPA.gov
📋

Violation History

Past 5 years — EPA SDWIS data

City of Mercedes has recorded 5 health-based violations out of 55 total violations over the past 5 years. 11 violations remain unresolved in EPA tracking records.

Total Violations (5 yr)
55
Health-Based Violations
5
Unresolved Violations
11
Boil Water Advisories
0
Compliance Risk
Critical

Regulatory compliance risk for this utility is rated Critical based on past reporting and enforcement records.

⚗️

Contaminants Detected

Contaminants with health-based violations on record

EPA records identify 2 contaminants with health-based violations in the past 5 years: Stage 1 DBP Rule, Stage 2 DBP Rule.

Stage 1 DBP RuleStage 2 DBP Rule

⚖ Enforcement Actions

EPA or state regulators have issued 10 enforcement actions to address compliance lapses.
🌊

Water Source & Environmental Factors

Surface Water

This system draws water from lakes, rivers, or reservoirs. Surface water is treated to remove sediment, microorganisms, and chemical contaminants before reaching taps.

Water Source Type
Surface Water
EPA Radon Zone

Lower potential

Zone 3
Annual Flood Risk Cost

Estimated annual flood-related costs per property

$35
Energy Burden

% of household income spent on energy — indicator of older infrastructure

3.25%

EPA Radon Zone 3 — lower radon potential, though the EPA still recommends testing all homes.

Water Quality Testing in ZIP 78570

Tap Water & Well Testing Recommendations

Residents in ZIP code 78570 served by City of Mercedes can test tap water or private well systems to verify water purity. Testing detects hidden contaminants before they impact family health.

Tap Water Testing Steps

  • 1.Conduct a certified lead check if your home was constructed before 1986.
  • 2.Use certified lab testing kits rather than uncalibrated test strips for regulated compliance.
  • 3.Sample water from both your kitchen faucet and water heater to compare line purity.

Private Well Testing Steps

  • •Test for Coliform bacteria and Nitrates annually.
  • •Test for heavy metals, radon, and PFAS every 3 years.
  • •Send samples to a state-certified drinking water laboratory recognized by Texas Commission on Environmental Quality (TCEQ).
Certified Lab Testing: Always use an EPA-certified drinking water laboratory in TX for formal legal or real estate compliance testing.

🛡 What Should You Do? — ZIP 78570 Recommendations

  • ⚠ Use a certified NSF/ANSI 53 filter for drinking and cooking water if you have young children
  • ⚠ Never give unfiltered tap water to infants in formula — use certified bottled or filtered water
  • ⚠ Request a copy of the Consumer Confidence Report to see what was detected and when
  • ⚠ Call the EPA Safe Drinking Water Hotline: 1-800-426-4791

Recommended Water Treatment Systems:

🏺

NSF 53 Lead Pitcher Filter

Specifically certified to reduce lead and copper at the tap.

Lead Filter Guide →
⚗️

NSF 58 Under-Sink RO System

Advanced filtration for PFAS, fluoride, nitrates, and organic chemicals.

RO System Guide →

Frequently Asked Questions — ZIP 78570 Water Quality

Is tap water safe to drink in ZIP code 78570?+
Tap water in 78570 (Mercedes, TX) meets major standards but has a grade of C due to minor past violations. Vulnerable populations may want to use a certified filter as a precaution.
How do I get my water tested in ZIP 78570 (Mercedes, TX)?+
To test water quality in ZIP 78570, you can order a certified drinking water test kit or send water samples to an EPA/NELAP certified laboratory in TX. Certified testing checks for lead, coliform bacteria, nitrates, hardness, and PFAS that standard test strips miss. Contact Texas Commission on Environmental Quality (TCEQ) for a list of certified regional labs.
How hard is the tap water in 78570?+
Tap water in 78570 is classified as Very Hard with an estimated mineral hardness of 183 mg/L (10.7 GPG). A whole-home water softener system is strongly recommended to protect plumbing and home appliances.
Should I test private well water in 78570?+
Yes. Unlike municipal systems, private wells in 78570 are not regulated by the EPA or local utilities. Private well owners should test their water annually for coliform bacteria and nitrates, and every 3 to 5 years for heavy metals (lead, arsenic) and volatile organic compounds.
What is the lead level in 78570 tap water?+
The 90th percentile lead level in 78570 is 3.7 ppb. The EPA action level is 15 ppb. This is below the EPA action level.
Is there an active boil water notice in 78570?+
There are currently no active boil water advisories on record for 78570. Water treatment systems are operating within normal parameters.
Who provides tap water to 78570?+
Tap water in ZIP code 78570 is provided by City of Mercedes (EPA ID: TX1080007), serving approximately 16,258 residents.
What water filter should I use in 78570?+
Based on water metrics for 78570, we recommend Reverse Osmosis (PFAS & Lead). Look for certifications such as NSF/ANSI 53 (Chemical Contaminants), NSF/ANSI 42 (Aesthetic Effects).

Data Sources & Methodology

Water quality data for ZIP code 78570 is compiled from the EPA Safe Drinking Water Information System (SDWIS), EPA ECHO enforcement database, UCMR5 unregulated contaminant monitoring, and Consumer Confidence Reports filed by City of Mercedes. Safety scores are composite metrics derived from violation history, lead levels, enforcement actions, and infrastructure risk indicators. Data reflects a 5-year monitoring window. Last dataset update: 2024. View EPA source data →