PlainWater
Counties → California

San Luis Obispo County, California

Water Systems
167
Population Served
347,560
Total Violations
1,652
632 health-based
PFAS Detected
11
of 17 tested

Violation Analysis

74.9%
Systems with Violations
9.9
Avg Violations per System
38.3%
Health-Based Violations

Water Source Types

GW
28 systems (17%)
SW
22 systems (13%)

PFAS Contamination

17
Systems Tested
11
PFAS Detected
64.7%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

San Luis Obispo California water systems by violation status, EPA SDWIS records.

No violations on record (10) One or more violations (40)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Santa Margarita Recreation Area 50,001 0 -
San Luis Obispo Water Department 47,788 2 Clean
City of Paso Robles Water Division 31,176 9 Detected
Atascadero Mutual Water Co 30,618 3 Detected
City of Arroyo Grande Utilities Division 17,963 7 Detected
California Mens Colony 15,000 11 Clean
Nipomo Comm Services Dist 13,771 8 Clean
Morro Bay Pw Dept - Water Division 13,757 13 Clean
City of Grover Beach Public Works Dept 12,701 8 Clean
Brecon Estate 9,012 0 -
Pismo Beach Water Department 8,036 13 Clean
Templeton Csd 8,011 4 Detected
Oceano Comm Services Dist. 7,601 23 Clean
Los Osos Community Services District 7,086 3 Detected
Golden State Water Company - los Osos 5,924 0 Detected
Cambria Comm Services Dist 5,532 22 Clean
Golden State Water Company - Nipomo 4,506 0 Detected
Atascadero State Hospital 4,100 6 Detected
Woodlands Development 3,862 3 -
Grosso Kresser Winery 3,606 0 -
Heritage Ranch Csd 2,956 38 Clean
San Miguel Community Services District 2,600 2 -
Cayucos Beach Mutual Water Company 2,567 1 -
Morro Rock Mutual Water Co 2,181 1 -
Nacimiento Water Company 2,181 103 -
Golden State Water Company-Cypress Ridge 2,026 48 -
Avila Beach Community Services District 1,630 0 -
Tiger Water Supply 1,600 5 -
San Miguelito MWC 1,600 5 -
Lopez Project 1,569 5 -
County of Monterey-Lake Nacimiento 1,521 10 -
Golden State Water Company - Edna 1,493 2 -
Caltrans - Shandon Rest Stop 1,300 10 -
Slo Cwwd No. 23 - Santa Margarita 1,291 2 -
Pg&e 1,200 26 -
Slocsa #10a - Cayucos 1,200 0 -
Slo CSA No. 16 - Shandon 1,085 0 -
Daou Vineyards, LLC 1,025 2 -
Montana de Oro State Park 990 7 -
Laureate Water Company 700 14 -
Coastal Christian School 650 0 -
Mesa Dunes Mobile Home Estates 600 15 -
S & T Mutual Water Company 591 3 -
Woodland Park Mutual Water Co 538 21 -
Hearst Memorial State Beach 500 2 -
Walnut Hills Mutual Water Co 486 4 -
San Simeon Csd 462 8 -
Garden Farms C.w.d. 440 13 -
Los Robles Mobile Home Estates 420 4 -
Vines R.V. Resort 400 0 -

Other Counties in California

Los Angeles County
276 systems · 10,109,089 served · 3,972 violations
San Diego County
197 systems · 3,744,323 served · 4,832 violations
Orange County
46 systems · 3,201,893 served · 507 violations
Riverside County
201 systems · 2,839,125 served · 6,103 violations
San Bernardino County
318 systems · 2,830,626 served · 4,611 violations
Alameda County
27 systems · 2,249,634 served · 275 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in San Luis Obispo County? ▼
San Luis Obispo County has 1,652 total drinking water violations across 167 water systems, of which 632 are health-based violations. 74.9% of systems have at least one violation.
How many people get water from San Luis Obispo County systems? ▼
Water systems in San Luis Obispo County serve approximately 347,560 people through 167 public water systems.
Has PFAS been detected in San Luis Obispo County water? ▼
Of 17 water systems tested for PFAS in San Luis Obispo County, 11 had PFAS detected (64.7% detection rate).
What types of water sources supply San Luis Obispo County? ▼
Water systems in San Luis Obispo County use GW (28 systems), SW (22 systems) as their primary water sources.
Are health-based violations serious? ▼
Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 38.3% of San Luis Obispo County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.