San Luis Obispo Water Department
EPA ID: CA4010009 · 47,788 people served · 10 ZIP codes
Records for San Luis Obispo Water Department show 2 violations over the monitored period, with every finding addressed and officially closed — the provider, which serves approximately 47,788 people, carries no outstanding enforcement actions in the current EPA dataset and meets all applicable drinking water requirements.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for San Luis Obispo Water Department Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The San Luis Obispo Water Department serves a community with a median household income of $82,837 and an estimated 67,164 residents across its service area. Approximately 56% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
San Luis Obispo Water Department's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in San Luis Obispo County, California rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How San Luis Obispo Water Department compares to EPA limits
What This Means For You
Consumer Confidence Report Rule at 1 mg/L exceeds the EPA maximum of mg/L.
E. coli at 1 Zero tolerance (any positive sample triggers immediate action) exceeds the EPA maximum of Zero tolerance (any positive sample triggers immediate action). Severe GI illness; potentially fatal kidney failure in children. Consider UV disinfection (99.99%) filtration.
E. coli was detected in this water system. UV disinfection (99.99%) filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
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Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
San Luis Obispo Water Department (EPA ID: CA4010009) is a community water system in California that serves approximately 47,788 people from surface water sources.
This system provides water to 10 ZIP codes across 3 communities.
Average Home Safety Score: B (79/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| April 1, 2025 | Consumer Confidence Report Rule | Health-based | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Consumer Confidence Report Rule | Reporting Failure | 1 | Yes |
| E. coli | Microbiological | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 93401 | 0.0011 mg/L | No | N/A |
| 93403 | 0.0011 mg/L | No | N/A |
| 93405 | 0.0011 mg/L | No | N/A |
| 93406 | 0.0011 mg/L | No | N/A |
| 93407 | 0.0011 mg/L | No | N/A |
| 93408 | 0.0011 mg/L | No | N/A |
| 93410 | 0.0011 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 4 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 6 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 93401 — San Luis Obispo
- 93403 — San Luis Obispo
- 93405 — San Luis Obispo
- 93406 — San Luis Obispo
- 93407 — San Luis Obispo
- 93408 — San Luis Obispo
- 93409 — San Luis Obispo
- 93410 — San Luis Obispo
- 93432 — Creston
- 93453 — Santa Margarita
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for San Luis Obispo Water Department (CA4010009) on EPA.gov.
Frequently Asked Questions
Is San Luis Obispo Water Department water safe to drink?
San Luis Obispo Water Department has recorded 1 health-based violation in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does San Luis Obispo Water Department serve?
San Luis Obispo Water Department serves approximately 47,788 people across 10 ZIP codes in California.
Where does San Luis Obispo Water Department get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
San Luis Obispo Water Department (EPA ID: CA4010009) — request the latest Consumer Confidence Report or ask about specific contaminants.