D36/100
CASTLE ROCK MUNICIPAL WATER — Water Quality Report 2026
Serving 4,367 people · Washington
Water Source
Surface Water
County
—
System ID
WA5311800
Violations
45
Contaminant Test Results
2 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.40 mg/L | 1.30 mg/L | Over Limit |
Lead (90th percentile) | 0.005 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
2
Violations (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: January 1, 2023 – December 31, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: January 1, 2023 – December 31, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About CASTLE ROCK MUNICIPAL WATER
Is CASTLE ROCK MUNICIPAL WATER water safe to drink?
CASTLE ROCK MUNICIPAL WATER water receives a grade of D (36/100), which is considered poor. 1 contaminant(s) exceed EPA legal limits and 45 violation(s) are on record. Customers may want to consider using a water filter.
What contaminants has CASTLE ROCK MUNICIPAL WATER detected?
52 contaminants were tested in CASTLE ROCK MUNICIPAL WATER's water. Notable contaminants include Copper (90th percentile), Lead (90th percentile). 1 exceed EPA legal limits (MCLs). 2 exceed EPA health goals (MCLGs).
Does CASTLE ROCK MUNICIPAL WATER have any EPA violations?
Yes, CASTLE ROCK MUNICIPAL WATER has 45 EPA violation(s) on record, with the most recent in 2023. Violation types include MR, TT. 2 are health-based violations.
How many people does CASTLE ROCK MUNICIPAL WATER serve?
CASTLE ROCK MUNICIPAL WATER serves approximately 4,367 people, Washington.
What type of water does CASTLE ROCK MUNICIPAL WATER provide?
CASTLE ROCK MUNICIPAL WATER sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is WA5311800.
How does CASTLE ROCK MUNICIPAL WATER compare to other utilities in Washington?
CASTLE ROCK MUNICIPAL WATER scores 36/100 with a grade of D (poor). This score suggests significant water quality concerns relative to other utilities. Visit our Washington state page for a full comparison of water systems.