A
85

Excellent Water Quality

Altadena, CA 91003

Los Angeles County · Population served: 9,215 · Data updated March 2026

Water Systems Serving This Area

🏔
RUBIO CANON LAND & WATER ASSOCIATION
Surface water · Pop. 9,215
PWSID: CA1910140

PFAS / Forever Chemicals

7 detected 3 above EPA limits
CompoundLevelEPA MCLHealth GuidelineStatus
PFOS19.0 ppt4 ppt4 pptExceeded
PFHxS11.0 ppt10 ppt10 pptExceeded
PFOA8.5 ppt4 ppt4 pptExceeded
PFBA5.7 pptNo standard500 pptUnregulated
PFBS3.5 ppt2000 ppt100 pptBelow limit
PFPeA3.5 pptNo standardUnregulated
PFHxA3.1 pptNo standard400 pptUnregulated

Water Quality Summary

Understanding Your Water in Altadena

Tap water quality in Altadena, California (91003) receives an overall grade of A (Excellent) with a score of 85 out of 100, based on analysis of EPA compliance data, contaminant testing, and violation history. This is roughly in line with the California state average of 81. The area is served by Rubio Canon Land & Water Association, a surface water system providing water to approximately 9,215 people. Notably, 3 PFAS compounds exceed EPA limits — a significant concern given the persistent nature of these chemicals. The area has a clean violation record over the past 5 years — a positive indicator of consistent water quality management.

Your Score 85/100 A
vs State 4 pts above California avg (81)
vs National 10 pts above national avg (75)

What a Grade A Means

A score of 85/100 means the water supply in Altadena, CA meets or exceeds all EPA standards with minimal issues. Contaminant levels are well within safe limits, and the water system has maintained a strong compliance record. While no water supply is guaranteed perfect at the tap due to household plumbing, this is among the best-scoring areas in the country.

Surface water: sourced from rivers, lakes, or reservoirs

Common Questions

Frequently Asked Questions

Based on EPA data, tap water in Altadena, California receives a grade of A (Excellent) with a score of 85/100. This indicates the water meets federal standards and has relatively few concerns. However, individual homes may still have localized issues such as lead from old plumbing.

ZIP code 91003 is served by 1 water system using surface water sources, providing water to approximately 9,215 people. Surface water systems are more susceptible to contamination from agricultural runoff, industrial discharge, and weather events, but typically undergo more extensive treatment including filtration and disinfection.

No lead data is currently available for ZIP code 91003. This may mean lead testing results haven't been reported recently, or the serving water system uses monitoring waivers. You can request a free lead test kit from most water utilities or purchase a certified home testing kit.

Yes — 7 PFAS compounds were detected in water serving Altadena, California, and 3 exceed EPA maximum contaminant levels. PFAS are persistent chemicals linked to cancer, immune system effects, and developmental issues. A reverse osmosis or activated carbon filter certified for PFAS removal is recommended.

Water systems serving Altadena, California have zero violations in the last 5 years. This is a positive indicator of consistent regulatory compliance and water quality management.

Based on detected contaminants (PFAS), residents in Altadena, California should consider: Reverse osmosis (RO) system — most effective for PFAS, lead, and other contaminants. Always look for filters with NSF/ANSI certification for the specific contaminants you want to remove.

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