Longmont, CO Tap Water Quality

Water quality in Longmont, CO is currently rated with a moderate C grade (average score: 62/100 across 4 ZIP codes). This rating indicates that while the water provided by City of Longmont is treated and regulated, there have been notable compliance issues or contaminant detections recently. Residents should stay informed about the specific challenges affecting their local supply.

A major factor in Longmont'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 4 ZIP codes in Longmont 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.