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Official EPA SDWIS Verified ReportWater Quality & Testing GuideHistorical Record: No Recorded SDWIS Violations

ZIP Code 74531 Water Quality & Testing Report

Calvin, OK · Hughes 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 74531 (Calvin, OK)?

Yes, tap water in ZIP code 74531 (Calvin, OK) is safe to drink under EPA Safe Drinking Water Act standards. Supplied by Hughes Company Rwd #6 (gerty), the area earns an EPA Safety Grade of A (98/100) with 0 health violations, 3.1 ppb lead, and hard (169 mg/L / 9.9 GPG) water.

Safety Score
A

Water Safety Grade

Excellent — Meets all EPA standards

Health Violations

0

Total Violations

3

Lead Risk

Moderate

Contaminants

0

About Tap Water in ZIP Code 74531

Tap water in ZIP code 74531 (Calvin, OK) is distributed by Hughes Company Rwd #6 (gerty) (EPA ID: OK2003224), serving approximately 2,180 residents. Based on EPA Safe Drinking Water Act compliance records, this system receives a water safety grade of A with a composite quality score of 98/100.

Water System

Hughes Company Rwd #6 (gerty)

EPA ID: OK2003224

Water Source

Ground Water

Population Served

2,180 residents

County

Hughes County County, Oklahoma

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Lead Levels in ZIP 74531

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

Lead Level: 3.1 ppb — Very Low

The 90th percentile lead level in 74531 is 3.1 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 74531 is rated Moderate. EPA models estimate a 43% exposure probability based on housing and infrastructure age.

Lead Level (90th percentile)
3.10 ppb (0.0031 mg/L)
Copper Level (90th percentile)

EPA action level: 1.3 mg/L

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

EPA model estimate based on housing age and infrastructure

43%
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.
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Water Hardness & Mineral Content

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

Classification: Hard9.9 GPG · 169 mg/L

Water in ZIP 74531 is Hard (169 mg/L / 9.9 GPG). Residents may notice white mineral spots on glassware, reduced soap efficiency, and mineral scale on faucets and showerheads.

Recommendation: An ion-exchange water softener or descaler is recommended to prolong the life of water heaters, dishwashers, and plumbing.
Hardness (GPG)

Grains per gallon

9.9 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

169 mg/L
Appliance Scaling Risk
High / Severe

Official EPA SDWIS Database Entry

Utility: Hughes Company Rwd #6 (gerty) · PWSID: OK2003224

Verify on EPA.gov
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Violation History

Past 5 years — EPA SDWIS data

Hughes Company Rwd #6 (gerty) has recorded 3 violations, but none are health-based (e.g., administrative or monitoring infractions).

Total Violations (5 yr)
3
Health-Based Violations
0
Unresolved Violations
0
Boil Water Advisories
0
Compliance Risk
High

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

⚗️

Contaminants Detected

Contaminants with health-based violations on record

No health-based contaminant violations are on record for ZIP code 74531 under the Safe Drinking Water Act.

⚖ Enforcement Actions

EPA or state regulators have issued 10 enforcement actions to address compliance lapses.
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Water Source & Environmental Factors

Ground Water

This system draws water from underground aquifers. Groundwater is naturally filtered through soil and rock, but can still contain naturally occurring minerals like arsenic, radium, or nitrates.

Water Source Type
Ground Water
EPA Radon Zone

Lower potential

Zone 3
Energy Burden

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

3.36%

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

Water Quality Testing in ZIP 74531

Tap Water & Well Testing Recommendations

Residents in ZIP code 74531 served by Hughes Company Rwd #6 (gerty) 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 Oklahoma Department of Environmental Quality.
Certified Lab Testing: Always use an EPA-certified drinking water laboratory in OK for formal legal or real estate compliance testing.

🛡 What Should You Do? — ZIP 74531 Recommendations

  • ✓ Run cold water for 30 seconds each morning before use — especially if pipes are old
  • ✓ Request your annual Consumer Confidence Report from Hughes Company Rwd #6 (gerty)
  • ✓ If your home was built before 1986, consider testing your own tap for lead
  • ✓ Use a pitcher filter (NSF/ANSI 42 certified) for improved taste

Recommended Taste & Safety Filter:

🚰

NSF/ANSI 53 Certified Pitcher Filter

Best for removing aesthetic chlorine, odors, and low-level heavy metals.

Filter Selection Guide →

Frequently Asked Questions — ZIP 74531 Water Quality

Is tap water safe to drink in ZIP code 74531?+
Yes — tap water in 74531 (Calvin, OK) meets EPA standards with a water safety grade of A. No health-based violations are on record in the past 5 years.
How do I get my water tested in ZIP 74531 (Calvin, OK)?+
To test water quality in ZIP 74531, you can order a certified drinking water test kit or send water samples to an EPA/NELAP certified laboratory in OK. Certified testing checks for lead, coliform bacteria, nitrates, hardness, and PFAS that standard test strips miss. Contact Oklahoma Department of Environmental Quality for a list of certified regional labs.
How hard is the tap water in 74531?+
Tap water in 74531 is classified as Hard with an estimated mineral hardness of 169 mg/L (9.9 GPG). An ion-exchange water softener or descaler is recommended to prolong the life of water heaters, dishwashers, and plumbing.
Should I test private well water in 74531?+
Yes. Unlike municipal systems, private wells in 74531 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 74531 tap water?+
The 90th percentile lead level in 74531 is 3.1 ppb. The EPA action level is 15 ppb. This is below the EPA action level.
Is there an active boil water notice in 74531?+
There are currently no active boil water advisories on record for 74531. Water treatment systems are operating within normal parameters.
Who provides tap water to 74531?+
Tap water in ZIP code 74531 is provided by Hughes Company Rwd #6 (gerty) (EPA ID: OK2003224), serving approximately 2,180 residents.
What water filter should I use in 74531?+
Based on water metrics for 74531, we recommend None / Standard Pitcher. Look for certifications such as NSF/ANSI 42 (Chlorine, Taste & Odor).

Data Sources & Methodology

Water quality data for ZIP code 74531 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 Hughes Company Rwd #6 (gerty). 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 →