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

ZIP Code 99349 Water Quality & Testing Report

Mattawa, WA · Grant County County · Updated for 2026

Quick EPA Verified Answer

Is Tap Water Safe to Drink in ZIP 99349 (Mattawa, WA)?

Yes, tap water in ZIP code 99349 (Mattawa, WA) is safe to drink under EPA Safe Drinking Water Act standards. Supplied by City of Mattawa, the area earns an EPA Safety Grade of B (82/100) with 1 health violations, 0.9 ppb lead, and moderately hard (82 mg/L / 4.8 GPG) water.

Safety Score
B

Water Safety Grade

Good — Minor issues on record

Health Violations

1

Total Violations

12

Lead Risk

Low

Contaminants

1

About Tap Water in ZIP Code 99349

Tap water in ZIP code 99349 (Mattawa, WA) is distributed by City of Mattawa (EPA ID: WA5352000), serving approximately 5,015 residents. Based on EPA Safe Drinking Water Act compliance records, this system receives a water safety grade of B with a composite quality score of 82/100.

Water System

City of Mattawa

EPA ID: WA5352000

Water Source

Ground Water

Population Served

5,015 residents

County

Grant County County, Washington

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Lead Levels in ZIP 99349

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

Lead Level: 0.9 ppb — Very Low

The 90th percentile lead level in 99349 is 0.9 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 99349 is rated Low. EPA models estimate a 15% exposure probability based on housing and infrastructure age.

Lead Level (90th percentile)
0.90 ppb (0.0009 mg/L)
Lead Exposure Risk Rating
Low
Lead Exposure Probability

EPA model estimate based on housing age and infrastructure

15%
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: Moderately Hard4.8 GPG · 82 mg/L

Water in ZIP 99349 is Moderately Hard (82 mg/L / 4.8 GPG). It contains beneficial natural minerals like calcium and magnesium without causing heavy scale accumulation.

Recommendation: A water softener is optional. Regular maintenance of hot water appliances is recommended.
Hardness (GPG)

Grains per gallon

4.8 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

82 mg/L
Appliance Scaling Risk
Low / Moderate

Official EPA SDWIS Database Entry

Utility: City of Mattawa · PWSID: WA5352000

Verify on EPA.gov
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Violation History

Past 5 years — EPA SDWIS data

City of Mattawa has recorded 1 health-based violation out of 12 total violations over the past 5 years. 2 violations remain unresolved in EPA tracking records.

Total Violations (5 yr)
12
Health-Based Violations
1
Unresolved Violations
2
Boil Water Advisories
0
Compliance Risk
Critical

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

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Contaminants Detected

Contaminants with health-based violations on record

EPA records identify 1 contaminant with health-based violations in the past 5 years: Consumer Confidence Report Rule.

Consumer Confidence Report Rule

⚖ 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

Moderate potential

Zone 2
Energy Burden

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

6.95%

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

Water Quality Testing in ZIP 99349

Tap Water & Well Testing Recommendations

Residents in ZIP code 99349 served by City of Mattawa 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 Washington State Department of Health.
Certified Lab Testing: Always use an EPA-certified drinking water laboratory in WA for formal legal or real estate compliance testing.

🛡 What Should You Do? — ZIP 99349 Recommendations

  • ✓ Run cold water for 30 seconds each morning before use — especially if pipes are old
  • ✓ Request your annual Consumer Confidence Report from City of Mattawa
  • ✓ 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 99349 Water Quality

Is tap water safe to drink in ZIP code 99349?+
Yes — tap water in 99349 (Mattawa, WA) meets EPA standards with a water safety grade of B. No health-based violations are on record in the past 5 years.
How do I get my water tested in ZIP 99349 (Mattawa, WA)?+
To test water quality in ZIP 99349, you can order a certified drinking water test kit or send water samples to an EPA/NELAP certified laboratory in WA. Certified testing checks for lead, coliform bacteria, nitrates, hardness, and PFAS that standard test strips miss. Contact Washington State Department of Health for a list of certified regional labs.
How hard is the tap water in 99349?+
Tap water in 99349 is classified as Moderately Hard with an estimated mineral hardness of 82 mg/L (4.8 GPG). A water softener is optional. Regular maintenance of hot water appliances is recommended.
Should I test private well water in 99349?+
Yes. Unlike municipal systems, private wells in 99349 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 99349 tap water?+
The 90th percentile lead level in 99349 is 0.9 ppb. The EPA action level is 15 ppb. This is below the EPA action level.
Is there an active boil water notice in 99349?+
There are currently no active boil water advisories on record for 99349. Water treatment systems are operating within normal parameters.
Who provides tap water to 99349?+
Tap water in ZIP code 99349 is provided by City of Mattawa (EPA ID: WA5352000), serving approximately 5,015 residents.
What water filter should I use in 99349?+
Based on water metrics for 99349, 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 99349 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 Mattawa. 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 →