Water Quality in Maple Valley, WA: 4 Violations — Grade B
Grade B · Score 78/100 · 5 water systems · Updated 2026-05-03
Maple Valley's water is mostly safe. Minor violations exist but are primarily monitoring-related.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Maple Valley in WA has 4 EPA water violations documented — the compliance history below covers what was flagged and which local systems are associated with each finding.
Water Quality by ZIP Code in Maple Valley
Water quality varies across Maple Valley's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 98038 | B | 78 | 4 | 0 | View report → |
Water Quality Overview
Maple Valley, Washington receives a water quality grade of B with an overall score of 78 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Maple Valley have accumulated 4 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 29,097 people.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, Maple Valley's water systems meet the vast majority of federal requirements. Minor violations may exist but typically relate to monitoring or reporting rather than health-based standards.
Lead Levels
The average 90th percentile lead level across Maple Valley water systems is 0.0013 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
Water Systems Serving Maple Valley
Maple Valley is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 29,097 people across 1 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 6 enforcement actions against water systems serving Maple Valley. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Maple Valley
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Maple Valley Water Systems
The following contaminants have been detected or caused violations across Maple Valley's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | N/A | 1 | 1 | No |
| Lead | Inorganic | 0.015 mg/L | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 6 enforcement actions against water systems serving Maple Valley. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-30 | State Order Extension |
| 2025-09-25 | State Order Extension |
| 2025-06-03 | State Order Extension |
| 2024-08-12 | State Order Extension |
| 2023-08-17 | State Order Extension |
| 2021-05-20 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-30.
Maple Valley vs. Nearby Washington Cities
How Maple Valley's water quality compares to similar cities in Washington:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Maple Valley | B | 4 | 5 | 29,097 |
| Retsil | C | 0 | 1 | 28,928 |
| South Colby | C | 0 | 1 | 28,928 |
| Southworth | C | 0 | 1 | 28,928 |
Common Questions About Maple Valley Water
These are the most common questions residents search for about water quality in Maple Valley, Washington:
Is Maple Valley water hard or soft? Water hardness varies by source. Maple Valley's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Maple Valley tap water? Maple Valley's water receives a grade of B (78/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Maple Valley? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Maple Valley vs. Washington Average
Understanding how Maple Valley compares to the broader Washington average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Maple Valley.
ZIP Codes in Maple Valley
Maple Valley spans 1 ZIP code. The ZIP with the lowest water quality score is 98038. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.
Frequently Asked Questions
Your Water is Safe — Here's How to Keep It That Way
Grade B is excellent news. Here's what proactive homeowners do to maintain water quality:
Annual Water Testing
EPA recommends annual testing even with clean water. Home test kits: $20-$50. Catches changes before they become problems.
Maintenance Filtration
A basic carbon filter removes chlorine taste and catches emerging contaminants like PFAS that aren't yet fully regulated.
Plumbing Check
Even safe city water picks up lead from home pipes. If your home was built before 1986, a one-time pipe inspection is recommended.