SGV Water Quality
The San Gabriel Valley sits atop one of the most contaminated groundwater basins in the United States. Four active EPA Superfund sites, decades of industrial pollution, and regulatory limits set far above health guidelines mean that "legal" does not mean "safe" for SGV residents.
Important: Legal compliance does not equal safety.
Federal and California legal limits for many contaminants have not been updated in nearly 20 years. EWG's health guidelines are based on current peer-reviewed science and are often 10–500x stricter than legal limits. Your tap water may pass government tests while still containing contaminants at levels associated with increased cancer risk.
Contaminants of Concern in the SGV
These contaminants have been detected in SGV water supplies at levels exceeding EWG health guidelines. Data sourced from EWG's Tap Water Database and EPA Superfund records.
Data sources: EWG Tap Water Database (2021–2023 utility data), EPA Superfund Site Profiles, California State Water Resources Control Board. Detected levels represent annual utility averages from the most recent reporting period. Search your zip code on EWG for the most current data for your specific utility.
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