B74/100
Los Osos Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 7,086 residents · California
What's In Los Osos's Tap Water?
52
Contaminants Tested
3
Exceed EPA Limits
0
Above EPA Goals
3 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.47 mg/L | 1.30 mg/L | Over Limit |
PFOA | 0.015 µg/L | 0.004 µg/L | Over Limit |
PFOS | 0.012 µg/L | 0.004 µg/L | Over Limit |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2019.
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
LOS OSOS COMMUNITY SERVICES DISTRICT
Population Served
7,086
Water Source
Groundwater
System ID
CA4010016
Frequently Asked Questions About Los Osos Water
Is Los Osos tap water safe to drink?
Los Osos, California tap water receives a grade of B (74/100), which is considered good. Out of 52 contaminants tested, 3 exceed EPA maximum contaminant levels (MCLs) and 3 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Los Osos's water?
Of the 52 contaminants tested in Los Osos's water supply, the most notable include PFOA, PFOS, Copper (90th percentile). 3 contaminant(s) exceed EPA legal limits (MCLs). 3 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Los Osos have any water quality violations?
Yes, Los Osos has 2 EPA violation(s) on record, with the most recent in 2019. Violation types include MR. None of these are classified as health-based violations.
Do I need a water filter in Los Osos?
Based on EPA data, using a water filter in Los Osos is recommended. 3 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Los Osos's tap water come from?
Los Osos's drinking water is sourced from groundwater and supplied by LOS OSOS COMMUNITY SERVICES DISTRICT. The system serves approximately 7,086 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.
How often is Los Osos'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. Los Osos'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 Los Osos's water compare to other cities in California?
Los Osos's water quality score of 74/100 earns a grade of B, which is considered good. This is an above-average score compared to many cities nationwide. Visit our California state page to see how all cities in the state compare.
What should I do if I'm concerned about Los Osos's water quality?
If you have concerns about Los Osos'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 (LOS OSOS COMMUNITY SERVICES DISTRICT) 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.