A88/100
Mountlake Terrace Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 26,402 residents · Washington
What's In Mountlake Terrace's Tap Water?
68
Contaminants Tested
0
Exceed EPA Limits
0
Above EPA Goals
EPA Violation History
1
Violation (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Surface water treatment technique failure
When: July 1, 2024 – February 20, 2025Enforcement: 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
Water Utility Details
MOUNTLAKE TERRACE CITY OF
Population Served
26,402
Water Source
Purchased Surface Water
System ID
WA5357250
Frequently Asked Questions About Mountlake Terrace Water
Is Mountlake Terrace tap water safe to drink?
Mountlake Terrace, Washington tap water receives a grade of A (88/100), which is considered excellent. Out of 68 contaminants tested, none exceed EPA maximum contaminant levels (MCLs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Mountlake Terrace's water?
68 contaminants were tested in Mountlake Terrace's water supply. No contaminants exceed EPA legal limits (MCLs) or health goals (MCLGs), which is a positive indicator of water quality.
Does Mountlake Terrace have any water quality violations?
Yes, Mountlake Terrace has 12 EPA violation(s) on record, with the most recent in 2024. Violation types include Other, MR. None of these are classified as health-based violations.
Do I need a water filter in Mountlake Terrace?
Mountlake Terrace water meets EPA standards, so a filter is not strictly necessary. However, some residents prefer the added security of a water filter. EPA health goals (MCLGs) are stricter than legal limits and are set at levels with zero expected health risk. All contaminants are within health goals.
Where does Mountlake Terrace's tap water come from?
Mountlake Terrace's drinking water is sourced from purchased surface water and supplied by MOUNTLAKE TERRACE CITY OF. The system serves approximately 26,402 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Mountlake Terrace's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Mountlake Terrace's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Mountlake Terrace's water compare to other cities in Washington?
Mountlake Terrace's water quality score of 88/100 earns a grade of A, which is considered excellent. This places Mountlake Terrace among the better-performing water systems in Washington. Visit our Washington state page to see how all cities in the state compare.
What should I do if I'm concerned about Mountlake Terrace's water quality?
If you have concerns about Mountlake Terrace's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (MOUNTLAKE TERRACE CITY OF) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.