Denver’s tap water is generally considered safe and of high quality for consumption. Denver Water is responsible for sourcing, treating, and delivering this water to approximately 1.5 million people in the metro area. The utility manages an extensive system designed to ensure every glass meets stringent quality standards. This high quality reflects the pristine source water and rigorous treatment protocols in place.
The Direct Answer: Safety and Quality Standards
Denver’s drinking water consistently meets or surpasses all federal and state safety requirements. The system is regulated by the U.S. Environmental Protection Agency (EPA) and the Colorado Department of Public Health and Environment (CDPHE). Compliance requires continuous, comprehensive monitoring of the water quality. Denver Water performs over 145,000 tests annually, ensuring the water remains free of harmful contaminants from its mountain sources to the customer’s tap. Results are transparently published in an annual Water Quality Report, confirming the public water supply is safe to drink straight from the tap.
Where Does Denver’s Water Come From?
The vast majority of Denver’s water originates as high-altitude mountain snowmelt in the Rocky Mountains. This source water is collected across a 4,000-square-mile watershed that spans multiple counties. The utility manages two primary collection systems, with about 80% of the supply coming from the South System, which includes the upper South Platte and Blue River watersheds.
Water travels through an intricate network of reservoirs and tunnels, including the 23-mile Roberts Tunnel, which moves water across the Continental Divide from Dillon Reservoir. Key storage reservoirs like Gross and Dillon hold the snowmelt before it reaches the city’s treatment plants. Once the water arrives at a treatment facility, it undergoes a multi-step purification process to remove impurities:
- Coagulation and flocculation, where chemicals are added to clump tiny particles together.
- Sedimentation, where these heavier clumps settle to the bottom of large tanks and are removed.
- Filtration through materials like sand and anthracite coal to remove the smallest remaining particles.
- Disinfection, typically using chlorine, to eliminate disease-causing organisms and maintain water safety as it travels through the distribution pipes.
Common Local Water Concerns
The local water supply is classified as relatively soft to moderately hard, which is often considered a benefit. Hardness refers to the concentration of dissolved minerals, primarily calcium and magnesium. Since Denver’s supply comes from high-elevation snowmelt, it contains fewer dissolved minerals than water sourced from groundwater or mineral-rich rivers. This softer water means soap lathers easily and results in less scale buildup on household appliances.
Customers sometimes notice minor variations in the water’s taste or smell, which are aesthetic concerns, not safety issues. The most common cause is the residual chlorine used for disinfection, which protects water quality in the distribution system. A faint “bleachy” smell may be more noticeable seasonally or where water has remained in the pipes longer. Using a home filter or letting a pitcher of water sit in the refrigerator can mitigate these taste variations.
A highly localized concern involves lead, which is not present in the water leaving the treatment plants. Contamination occurs when water passes through old, privately-owned lead service lines connecting the water main to the home. Denver Water is actively addressing this through its Lead Reduction Program, which replaces these customer-owned lines with lead-free copper at no cost to the homeowner. The utility also adjusts the water’s pH level to create a protective coating inside the pipes, reducing the potential for lead to dissolve.