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

ZIP Code 85371 Water Quality & Testing Report

Poston, AZ · La Paz 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 85371 (Poston, AZ)?

Caution / Filtration Recommended: Tap water in ZIP code 85371 (Poston, AZ) has compliance concerns, earning an EPA Safety Grade of D (53/100) due to 0 health violation(s) and 0 ppb lead. While treated by EPCOR - LAKESIDE, residents are advised to use an NSF/ANSI 53 certified water filter for drinking and cooking.

Safety Score
D

Water Safety Grade

Poor — Multiple violations recorded

Health Violations

0

Total Violations

0

Lead Risk

High

Contaminants

0

About Tap Water in ZIP Code 85371

Tap water in ZIP code 85371 (Poston, AZ) is distributed by EPCOR - LAKESIDE (EPA ID: AZ0415010), serving approximately 1,775 residents. Based on EPA Safe Drinking Water Act compliance records, this system receives a water safety grade of D with a composite quality score of 53/100.

Water System

EPCOR - LAKESIDE

EPA ID: AZ0415010

Water Source

Surface Water

Population Served

1,775 residents

County

La Paz County County, Arizona

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Lead Levels in ZIP 85371

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 85371. Contact EPCOR - LAKESIDE to request lead testing results.

Lead exposure risk in 85371 is rated High. EPA models estimate a 60% exposure probability based on housing and infrastructure age.

Lead Exposure Risk Rating
High
Lead Exposure Probability

EPA model estimate based on housing age and infrastructure

60%
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 Hard11.1 GPG · 189 mg/L

Water in ZIP 85371 is Very Hard (189 mg/L / 11.1 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

11.1 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

189 mg/L
Appliance Scaling Risk
High / Severe

Official EPA SDWIS Database Entry

Utility: EPCOR - LAKESIDE · PWSID: AZ0415010

Verify on EPA.gov
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Violation History

Past 5 years — EPA SDWIS data

EPCOR - LAKESIDE 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 85371 under the Safe Drinking Water Act.

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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

Moderate potential

Zone 2
Energy Burden

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

9.8%

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

Water Quality Testing in ZIP 85371

Tap Water & Well Testing Recommendations

Residents in ZIP code 85371 served by EPCOR - LAKESIDE 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 Arizona Department of Environmental Quality.
Certified Lab Testing: Always use an EPA-certified drinking water laboratory in AZ for formal legal or real estate compliance testing.

🛡 What Should You Do? — ZIP 85371 Recommendations

  • 🚨 Install a certified NSF/ANSI 53 or 58 (reverse osmosis) filter immediately for drinking and cooking
  • 🚨 Do not give unfiltered water to children, pregnant women, or immunocompromised individuals
  • 🚨 Contact EPCOR - LAKESIDE to request the current violation status and corrective action plan
  • 🚨 Report concerns to your state environmental agency or call the EPA hotline: 1-800-426-4791
  • 🚨 Consider having your home's tap water independently tested by a certified lab

Recommended Water Treatment Systems:

REQUIRED FOR SAFETY
🏺

NSF 53 Lead Pitcher Filter

Certified to remove lead. Recommended for immediate protection.

Lead Filter Guide →
STRONGLY RECOMMENDED
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NSF 58 Under-Sink RO System

Reverse Osmosis system certified to remove PFAS, heavy metals, and viruses.

RO System Guide →

Frequently Asked Questions — ZIP 85371 Water Quality

Is tap water safe to drink in ZIP code 85371?+
Tap water in 85371 has a below-average safety grade of D due to compliance issues. We recommend using a certified water filter for drinking and cooking.
How do I get my water tested in ZIP 85371 (Poston, AZ)?+
To test water quality in ZIP 85371, you can order a certified drinking water test kit or send water samples to an EPA/NELAP certified laboratory in AZ. Certified testing checks for lead, coliform bacteria, nitrates, hardness, and PFAS that standard test strips miss. Contact Arizona Department of Environmental Quality for a list of certified regional labs.
How hard is the tap water in 85371?+
Tap water in 85371 is classified as Very Hard with an estimated mineral hardness of 189 mg/L (11.1 GPG). A whole-home water softener system is strongly recommended to protect plumbing and home appliances.
Should I test private well water in 85371?+
Yes. Unlike municipal systems, private wells in 85371 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 85371 tap water?+
Lead level data is not available in EPA records for 85371. Contact your utility for details.
Is there an active boil water notice in 85371?+
There are currently no active boil water advisories on record for 85371. Water treatment systems are operating within normal parameters.
Who provides tap water to 85371?+
Tap water in ZIP code 85371 is provided by EPCOR - LAKESIDE (EPA ID: AZ0415010), serving approximately 1,775 residents.
What water filter should I use in 85371?+
Based on water metrics for 85371, we recommend Lead & Microplastic Filter. Look for certifications such as NSF/ANSI 53 (Lead Reduction), NSF/ANSI 42 (Particulate/Taste).

Data Sources & Methodology

Water quality data for ZIP code 85371 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 EPCOR - LAKESIDE. 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 →