CheckPFAS

ZIP Code 93422

High Risk
High Risk PFAS Risk Level

PFAS above EPA limits detected

2 compounds exceed EPA Maximum Contaminant Levels in water serving this ZIP code. Standard pitcher filters like Brita do not remove PFAS. See filter recommendations below.

6
PFAS Detected
2
Above EPA Limits
1
Water System
558%
Highest % of MCL

Compounds Exceeding EPA Limits

PFOS Exceeds EPA limit
0 ppt MCL: 4 ppt 558% of limit
Detected: 22.30 ppt
PFOA Exceeds EPA limit
0 ppt MCL: 4 ppt 210% of limit
Detected: 8.40 ppt

What this means for you

One or more PFAS compounds were measured above the EPA's enforceable drinking water limit at a utility serving ZIP 93422. The EPA set these limits because long-term exposure at higher concentrations is associated with health effects including immune suppression, thyroid changes, and cancer risk increases. Standard pitcher filters (Brita, PUR) are not certified to remove PFAS. The most reliable at-home options are under-sink reverse osmosis systems or activated carbon block filters with an NSF/ANSI 58 certification specifically listing PFOA/PFOS reduction. Your water utility is required to bring levels into compliance by 2029 — filtering at the tap is the practical interim step if you'd like additional protection now.

ATASCADERO MUTUAL WATER CO

CA4010002 High Risk
Water Type
Groundwater
PFAS Detected
6
Above MCL
2
State
California
Data Period
2023–2025

PFAS Test Results

CompoundDetectedvs. EPA LimitEPA LimitStatus
PFOS
Perfluorooctane sulfonic acid
22.30ppt
558% of limit
4 ppt⚠ Exceeds MCL
PFOA
Perfluorooctanoic acid
8.40ppt
210% of limit
4 ppt⚠ Exceeds MCL
PFHxS
Perfluorohexane sulfonic acid
7.60ppt
76% of limit
10 pptBelow limit
lithium
20700.00pptNo federal limitUnregulated
PFBA
Perfluorobutanoic acid
10.00pptNo federal limitUnregulated
PFBS
Perfluorobutane sulfonic acid
9.40pptNo federal limitUnregulated
About this data
Source
EPA UCMR 5 (Unregulated Contaminant Monitoring Rule, 5th cycle)
Data released
January 2026
Sampling period
January 2023 – December 2025
Systems tested
~10,000 public water systems serving > 25 people
Water system (PWSID)
CA4010002
Detection threshold (MRL)
~1.5–2 ppt — "Not detected" means below this floor, not zero

Values shown are the highest single-sample concentration measured at entry points to the distribution system. Results reflect water quality at the treatment plant — aging pipes, building plumbing, and on-site storage can affect what actually reaches your tap.