C52/100
Lake Oswego Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 47,100 residents · Oregon
What's In Lake Oswego's Tap Water?
69
Contaminants Tested
0
Exceed EPA Limits
0
Above EPA Goals
EPA Violation History
2
Violations (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Surface water treatment technique failure
When: July 1, 2025 – September 2, 2025Enforcement: Resolving — corrective action underway
TIER 3Resolved
Surface water treatment technique failure
When: July 1, 2024 – July 3, 2024Enforcement: 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
LAKE OSWEGO MUNICIPAL WATER
Population Served
40,000
Water Source
Purchased Surface Water
System ID
OR4100457
LAKE GROVE WATER DISTRICT
Population Served
3,100
Water Source
Purchased Surface Water
System ID
OR4100460
RIVERGROVE WATER DISTRICT
Population Served
4,000
Water Source
Groundwater
System ID
OR4100461
Frequently Asked Questions About Lake Oswego Water
Is Lake Oswego tap water safe to drink?
Lake Oswego, Oregon tap water receives a grade of C (52/100), which is considered fair. 0 contaminant(s) exceed EPA maximum contaminant levels and 114 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.
What contaminants are in Lake Oswego's water?
Of the 69 contaminants tested in Lake Oswego's water supply, the most notable include Lead (90th percentile). No contaminants exceed EPA legal limits. 1 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Lake Oswego have any water quality violations?
Yes, Lake Oswego has 114 EPA violation(s) on record, with the most recent in 2025. Violation types include Other, MR, MCL. 6 of these are health-based violations, which are the most serious category.
Do I need a water filter in Lake Oswego?
Lake Oswego 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. 1 contaminant(s) exceed these stricter goals.
Where does Lake Oswego's tap water come from?
Lake Oswego's drinking water is sourced from purchased surface water and supplied by LAKE OSWEGO MUNICIPAL WATER and 2 other water system(s). The system serves approximately 47,100 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Lake Oswego'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. Lake Oswego'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 Lake Oswego's water compare to other cities in Oregon?
Lake Oswego's water quality score of 52/100 earns a grade of C, which is considered fair. This is a below-average score that indicates room for improvement. Visit our Oregon state page to see how all cities in the state compare.
What should I do if I'm concerned about Lake Oswego's water quality?
If you have concerns about Lake Oswego'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 (LAKE OSWEGO MUNICIPAL WATER) 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.