San Luis Obispo County | Public water system SAFER profile
Data date: July 31, 2026
Page 1 of 3

San Luis Obispo County public water systems

Status classification

Share of listed systems, followed by the count, reported population, and funding in each status.

Failing11%
At-Risk16%
Potentially At-Risk10%
Not At-Risk56%
Failing
At-Risk
Potentially At-Risk
Not At-Risk
Not Assessed
Systems
9
13
8
45
5
Population
4,032
28,704
4,541
232,535
1,604
Funding since 2017
$0
$0
$1M
$709K
$0

Key figures

80
public water systems
271,416
reported population
56%
serve 500 people or fewer
$2M
reported funding since 2017

System locations

Points show reported system locations. They do not represent service-area boundaries.

Each point represents one system record. Nearby or overlapping points can conceal multiple systems.

Summary

San Luis Obispo County has 80 public water systems in the SAFER dataset. Of these, 22 (28%) are classified as Failing or At-Risk.

Those systems report serving 32,736 people. The county profile is also shaped by small systems: 45 systems serve 500 people or fewer.

5 systems are listed as Not Assessed, serving 1,604 people, so Not Assessed should not be read as a low-risk classification.

Reported funding since 2017 totals $2M across 2 systems. Technical assistance funding totals $2M.

System counts and reported population

Not At-Risk systems make up 56% of listed systems and 86% of reported population. A few large systems drive that population, so it reaches more people than its system count suggests.

San Luis Obispo County | Public water system SAFER profile
Data date: July 31, 2026
Page 2 of 3

Risk profile

Risk in San Luis Obispo County is distributed across four dimensions. Water Quality contributes the largest share of the combined weighted risk score at 46%. Across all individual indicators, No intertie appears most often, affecting 50 of 75 assessed systems.

Water Quality
46%
of combined weighted risk
State 32% · ▲ 14 pts
Most common flagWater quality trends toward MCL
Accessibility
28%
of combined weighted risk
State 36% · ▼ 8 pts
Most common flagNo intertie
Affordability
16%
of combined weighted risk
State 17% · ▼ 1 pts
Most common flagHousehold socioeconomic burden
TMF Capacity
11%
of combined weighted risk
State 15% · ▼ 4 pts
Most common flagTotal net annual income

Water Quality

Water Quality accounts for 46% of the county’s combined weighted risk score. Water quality trends toward MCL appears in 42 of 75 assessed systems. Sources exceeding an MCL is next, appearing in 20 of 75 assessed systems.

Each indicator was assessed for 75 systems.

Accessibility

Accessibility accounts for 28% of the county’s combined weighted risk score. No intertie appears in 50 of 75 assessed systems. Drought and shortage risk is next, appearing in 18 of 64 assessed systems.

Indicator denominators range from 64 to 75 assessed systems.

Affordability

Affordability accounts for 16% of the county’s combined weighted risk score. Household socioeconomic burden appears in 23 of 75 assessed systems. Extreme water bill is next, appearing in 18 of 69 assessed systems.

Indicator denominators range from 69 to 75 assessed systems.

TMF Capacity

TMF Capacity accounts for 11% of the county’s combined weighted risk score. Total net annual income appears in 31 of 75 assessed systems. Operating ratio is next, appearing in 17 of 75 assessed systems.

Indicator denominators range from 70 to 75 assessed systems.

San Luis Obispo County | Public water system SAFER profile
Data date: July 31, 2026
Page 3 of 3

Patterns and context

The countywide totals hide important differences among systems. The panels below show how SAFER status varies by system size and service-area economic status, what conditions appear among Failing systems, and how reported funding is distributed across the 80 systems in San Luis Obispo County.

Status by system size

SAFER status within each population group

Among systems serving 500 people or fewer, 15 of 45 are Failing or At-Risk. This size group has the county’s highest concentration of high-concern classifications.

Economic context

Orange shows Failing or At-Risk systems within each service-area group

DAC and SDAC service areas contain 32 of 80 listed systems. Within those two groups, 11 systems are Failing or At-Risk.

Conditions among Failing systems

A system can appear under more than one condition

Frequently listed primary analytes

  • Nitrate4
  • Selenium3
  • Total Haloacetic Acids (Haa5)1

Among 9 Failing systems, 7 report primary MCL violation. The most frequently listed primary analytes are Nitrate, Selenium, and Total Haloacetic Acids (Haa5).

Reported funding

Totals since 2017 and number of systems reporting funding

Funding since 2017 totals $2M across 2 systems. Potentially At-Risk systems account for 61% of that total. Reported technical assistance funding adds $2M.

Key takeaways

28%

of systems are Failing or At-Risk

That represents 22 systems reporting service to 32,736 people. That is below the statewide average of 33%.

46%

of weighted risk comes from Water Quality

The most widespread individual flag is no intertie, found in 50 of 75 assessed systems. Statewide, Water Quality accounts for 32% of weighted risk.

56%

of systems serve 500 people or fewer

Small systems account for 45 of the county’s 80 listed systems. That is below the statewide average of 61%.