Cupertino, CA Tap Water Quality

The drinking water in Cupertino, CA generally meets all federal health standards, earning a solid B grade with a composite safety score of 71/100 across 2 ZIP codes. While the primary water utility, City of Cupertino, maintains adequate compliance with EPA regulations, there have been minor or administrative violations on record. Overall, residents receive safe tap water that is actively monitored by California State Water Resources Control Board.

A major factor in Cupertino's high rating is its flawless health-based violation record. Over the past 5 years of EPA tracking, local water systems have recorded zero health-based violations. This means that regulated contaminants—such as lead, arsenic, and harmful bacteria—have not exceeded the Maximum Contaminant Levels (MCLs) allowed by federal law. Drawing primarily from surface water, the city utilizes advanced filtration to maintain this standard.

Additionally, lead exposure risk remains a critical issue for certain neighborhoods. EPA data indicates that 1 out of 2 ZIP codes in Cupertino are rated as High or Very High risk for lead. This risk is often driven by aging homes with pre-1986 plumbing containing lead solder or service lines. Families in these areas should test their tap water and consider NSF/ANSI 53 certified filters.