States › California › San Luis Obispo County

San Luis Obispo County, CA Water Quality

Water quality data for 28 public water systems serving San Luis Obispo County, California — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 28 water systems · 29 cities
✅
Generally Safe — Most Systems Performing Well

The majority of water systems have no active violations and lead levels well below the federal action level.

B

San Luis Obispo County Earns a B

San Luis Obispo County: 29 communities across 28 water systems. 96.6% have no open violations.

  • Median lead where detected: 5.30 ppb
  • 7 communities with a lead detection, 21 reporting none detected
  • 4 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 96.6% of communities have no open violations
5.3 ppb
Median Lead Level
County-wide, 90th percentile
28
Water Systems
Active CWS & NTNCWS
96%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
⚠ Needs Attention
  • Atascadero
    Not detected
    PFAS above the limit at 1 of 4 sampling points
    D
  • Los Osos
    Not detected
    PFAS above the limit at 1 of 7 sampling points
    D
  • San Simeon
    45.00 ppb
    Lead above the 15 ppb action level
    D
  • Whitley Gardens
    0.50 ppb
    1 violation currently open
    C
  • Callender
    12.00 ppb
    12 health-based violations since 2015
    B
County Lead Level — Median 5.3 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 5.3 ppb — 35.3% of the federal action level
Systems by Lead Level
Under 5 ppb
3
5 – 10 ppb
1
10 – 15 ppb
3
No Data
22

All Cities in San Luis Obispo County

San Luis Obispo Not detected A
El Paso de Robles (Paso Robles) Not detected B
Atascadero Not detected D
Arroyo Grande Not detected B
Grover Beach Not detected B
Nipomo Not detected A
Morro Bay Not detected A
Pismo Beach Not detected B
Templeton Not detected A
Los Osos Not detected D
Oceano Not detected A
California Polytechnic State University Not reported B
Cambria Not detected B
San Miguel Not detected B
Lake Nacimiento Not detected B
Woodlands Not detected B
Los Ranchos Not detected B
Cayucos 5.30 ppb B
Santa Margarita Not detected B
Shandon Not detected B
Avila Beach Not detected B
Callender 12.00 ppb B
San Simeon 45.00 ppb D
Garden Farms 11.00 ppb B
Whitley Gardens 0.50 ppb C
Los Berros 1.50 ppb B
Oak Shores Not detected B
Edna 0.79 ppb B
Blacklake Not detected A
Showing 29 cities
No active violations Active violations

About San Luis Obispo County Drinking Water

San Luis Obispo County is served by 28 water systems covering 29 communities. 97% have no open violations.

Of the communities reporting lead results, 7 recorded a detection, with a median of 5.30 ppb — 35% of the federal action level. 21 reported none detected, which means below the laboratory limit rather than an absence of lead.

4 of 29 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded no significant deficiencies.

Frequently Asked Questions

Is San Luis Obispo County tap water safe to drink?▼
97% of communities have no open violation. 4 of 29 have PFAS above the federal limit, which is the main open concern.
What is the lead level in San Luis Obispo County?▼
Among communities with a detection the median is 5.30 ppb, 35% of the 15 ppb action level. 21 reported none detected and 1 reported no result.
How many water systems serve San Luis Obispo County?▼
28 community water systems serve 29 communities here.
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