Atascadero Mutual Water Company
EPA ID: CA4010002 · 30,618 people served · 5 ZIP codes
The five-year EPA compliance file for Atascadero Mutual Water Company contains 3 violations, each documented and subsequently closed — the utility now operates in full compliance and continues to supply approximately 30,618 residents with water meeting current federal standards, including both health-based and monitoring requirements.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Atascadero Mutual Water Company Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The Atascadero Mutual Water Company serves a community with a median household income of $88,135 and an estimated 49,020 residents across its service area. Approximately 57% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Atascadero Mutual Water Company's water is pumped from underground aquifers. Groundwater is naturally filtered through rock and soil, but it can be vulnerable to PFAS contamination, nitrates from agriculture, and industrial chemicals that seep into the water table.
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 Atascadero Mutual Water Company compares to EPA limits
What This Means For You
Lead at 3 mg/L (action level) exceeds the EPA maximum of 0.015 mg/L (action level). Brain damage in children, kidney & blood pressure in adults. Consider reverse osmosis filtration.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 12 detections recorded. 4 exceed federal EPA limits (4 ppt for PFOA/PFOS). 3 exceed state limits.
Lead was detected in this water system. reverse osmosis filtration can reduce exposure.
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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
Atascadero Mutual Water Company (EPA ID: CA4010002) is a community water system in California that serves approximately 30,618 people from groundwater sources.
This system provides water to 5 ZIP codes across 4 communities.
Average Home Safety Score: C (67/100)
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 |
|---|---|---|---|
| January 1, 2023 | Lead | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Lead | Inorganic | 3 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
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 1 additional ZIP inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Atascadero Mutual Water Company (CA4010002) on EPA.gov.
Frequently Asked Questions
Is Atascadero Mutual Water Company water safe to drink?
Atascadero Mutual Water Company has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does Atascadero Mutual Water Company serve?
Atascadero Mutual Water Company serves approximately 30,618 people across 5 ZIP codes in California.
Where does Atascadero Mutual Water Company get its water?
The primary water source is groundwater.
Federal UCMR5 PFAS Monitoring: Above Current MCL
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). One or more PFAS compounds were measured above the current state-enforceable MCL.
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:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
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
Atascadero Mutual Water Company (EPA ID: CA4010002) — request the latest Consumer Confidence Report or ask about specific contaminants.