Public water system · CA4010016
ActiveLos Osos Community Services District
At a glance
Los Osos Community Services District (PWSID CA4010016) is an active community water system in San Luis Obispo County, California. It reports serving 7,086 people through 2,776 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 2 violations for this system; none is health-based, and the most recent began in October 2019.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
7,086
Service connections
2,776
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Los Osos Community Services District compare with other water systems in San Luis Obispo County?
By EPA's size categories, Los Osos Community Services District is a medium system (3,301 to 10,000 people). San Luis Obispo County has 171 active public water systems. Its population served is about 3.5 times the county average of 2,038 people per system, and accounts for 2% of the 348,510 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active community water system reports serving 6,703 people, so Los Osos Community Services District is roughly in line with that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 6,179 California systems (83%) list groundwater as their primary source.
Who owns and regulates Los Osos Community Services District?
EPA lists Los Osos Community Services District as owned by a local government. The CA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 33 of the 171 active systems in San Luis Obispo County (19%) are also owned by a local government.
Does Los Osos Community Services District have drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in October 2019. The violations listed here began between June 1993 and October 2019. By type: 2 monitoring and reporting. The contaminant or rule involved most often is Lead and Copper Rule (2 of them). EPA lists 2 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2019-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1993-06-30 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
All 2 violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Los Osos Community Services District: frequently asked questions
Who runs Los Osos Community Services District?
Los Osos Community Services District (PWSID CA4010016) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Los Osos Community Services District serve?
Los Osos Community Services District reports serving 7,086 people through 2,776 service connections in San Luis Obispo County, California.
Where does Los Osos Community Services District get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Los Osos Community Services District have any drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in October 2019. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Los Osos Community Services District's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list 2 violations for this system; none is health-based, and the most recent began in October 2019. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Los Osos Community Services District's water quality report?
As a community water system, Los Osos Community Services District must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in San Luis Obispo County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Santa Margarita Recreation Area | San Luis Obispo | 50,001 | Transient non-community | Groundwater |
| San Luis Obispo Water Department | San Luis Obispo | 47,788 | Community | Surface water |
| City of Paso Robles Water Division | San Luis Obispo | 31,176 | Community | Surface water |
| Atascadero Mutual Water Co | San Luis Obispo | 30,618 | Community | Groundwater |
| City of Arroyo Grande Utilities Division | San Luis Obispo | 17,963 | Community | Purchased surface water |
| California Mens Colony | San Luis Obispo | 15,000 | Community | Surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Los Osos Community Services District, PWSID CA4010016, California”, https://aquacensus.com/water-systems/california/los-osos-community-services-district-ca4010016 (data as of October 1, 2026).