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WaterSafeCheck
Official EPA SDWIS Verified ReportWater Quality & Testing GuideStatus: Normal Operations

ZIP Code 76831 Water Quality & Testing Report

Castell, TX · Llano County County · Updated for 2026

Quick EPA Verified Answer

Is Tap Water Safe to Drink in ZIP 76831 (Castell, TX)?

Caution / Filtration Recommended: Tap water in ZIP code 76831 (Castell, TX) has compliance concerns, earning an EPA Safety Grade of C (63/100) due to 0 health violation(s) and 0 ppb lead. While treated by CITY OF MASON, 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

0

Total Violations

0

Lead Risk

N/A

Contaminants

0

About Tap Water in ZIP Code 76831

Tap water in ZIP code 76831 (Castell, TX) is distributed by CITY OF MASON (EPA ID: TX1600001), serving approximately 2,228 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 63/100.

Water System

CITY OF MASON

EPA ID: TX1600001

Water Source

Ground Water

Population Served

2,228 residents

County

Llano County County, Texas

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Lead Levels in ZIP 76831

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

Lead Data Not Available

Lead testing data was not found in EPA records for ZIP code 76831. Contact CITY OF MASON to request lead testing results.
Lead Exposure Risk Rating
Unknown
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: Very Hard13.7 GPG · 234 mg/L

Water in ZIP 76831 is Very Hard (234 mg/L / 13.7 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

13.7 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

234 mg/L
Appliance Scaling Risk
High / Severe

Official EPA SDWIS Database Entry

Utility: CITY OF MASON · PWSID: TX1600001

Verify on EPA.gov
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Violation History

Past 5 years — EPA SDWIS data

CITY OF MASON has recorded zero violations in the EPA compliance database over the past 5 years.

Total Violations (5 yr)
0
Health-Based Violations
0
Unresolved Violations
0
Boil Water Advisories
0
Compliance Risk
Unknown
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Contaminants Detected

Contaminants with health-based violations on record

No health-based contaminant violations are on record for ZIP code 76831 under the Safe Drinking Water Act.

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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

Moderate potential

Zone 2

EPA Radon Zone 2 — moderate radon potential. The EPA recommends testing your home regardless of zone designation.

Water Quality Testing in ZIP 76831

Tap Water & Well Testing Recommendations

Residents in ZIP code 76831 served by CITY OF MASON 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 76831 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:

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NSF 53 Lead Pitcher Filter

Specifically certified to reduce lead and copper at the tap.

Lead Filter Guide →
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NSF 58 Under-Sink RO System

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

RO System Guide →

Frequently Asked Questions — ZIP 76831 Water Quality

Is tap water safe to drink in ZIP code 76831?+
Tap water in 76831 (Castell, 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 76831 (Castell, TX)?+
To test water quality in ZIP 76831, 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 76831?+
Tap water in 76831 is classified as Very Hard with an estimated mineral hardness of 234 mg/L (13.7 GPG). A whole-home water softener system is strongly recommended to protect plumbing and home appliances.
Should I test private well water in 76831?+
Yes. Unlike municipal systems, private wells in 76831 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 76831 tap water?+
Lead level data is not available in EPA records for 76831. Contact your utility for details.
Is there an active boil water notice in 76831?+
There are currently no active boil water advisories on record for 76831. Water treatment systems are operating within normal parameters.
Who provides tap water to 76831?+
Tap water in ZIP code 76831 is provided by CITY OF MASON (EPA ID: TX1600001), serving approximately 2,228 residents.
What water filter should I use in 76831?+
Based on water metrics for 76831, 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 76831 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 MASON. 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 →