Denver tap water is safe to drink and consistently meets the rigorous quality standards set by federal and state regulatory bodies. Denver Water manages a comprehensive system that ensures quality from the source to the tap. The water is delivered to over 1.5 million customers throughout the metro area. A proactive, long-term program is in place to address potential issues arising from older, privately owned plumbing infrastructure.
Where Denver’s Water Originates
The source of Denver’s drinking water is high-quality mountain snowmelt that is collected across a vast watershed. The utility relies entirely on surface water from the South Platte River and Colorado River basins, which are fed by the Rocky Mountain snowpack. This water is collected from multiple river systems, including the Blue and Fraser Rivers, providing a resilient initial source.
Approximately half of the supply originates on the western side of the Continental Divide, where it is transferred through tunnels and a complex system of reservoirs to the eastern side for treatment. The water is stored in reservoirs, such as Dillon and Gross, before being routed to one of Denver Water’s treatment plants. Because the source water comes from protected, high-elevation areas with minimal development, the initial water quality is exceptionally high.
Treatment and Quality Testing Protocols
Before distribution, the raw water is processed at one of Denver Water’s treatment facilities using a multi-barrier approach. The process begins with coagulation and flocculation, where chemicals are added to clump together fine particles and organic matter. These heavier clumps are then allowed to settle out during the sedimentation phase.
The water then passes through filters composed of materials like sand and gravel, which effectively remove any remaining microscopic particles, including bacteria and parasites. The final step is disinfection, where chloramine—a combination of chlorine and ammonia—is added to kill any residual pathogens and maintain water safety as it travels through the distribution system.
The utility conducts an extensive testing program, collecting over 55,000 samples and performing nearly 200,000 water quality tests annually. This monitoring ensures the water meets all compliance standards upon leaving the treatment plants. Residents can review the full data on contaminants, test results, and compliance in the annual Consumer Confidence Report (CCR), which is published every spring.
Navigating Lead Service Lines and Home Plumbing
While the water leaving the treatment facility is lead-free, lead can enter the water supply through older infrastructure located between the water main and the home’s taps. This contamination risk is primarily associated with lead service lines—the pipe connecting the water main to the home—or internal plumbing components like brass fixtures and lead solder used before 1987. Denver Water has proactively addressed this risk by launching the comprehensive Lead Reduction Program (LRP) in 2020.
The LRP is a 15-year, no-cost initiative to replace an estimated 64,000 to 84,000 customer-owned lead service lines with new copper pipes. The program also involves adjusting the water’s pH level to increase its alkalinity. This strengthens the protective mineral coating inside all pipes and reduces the potential for lead to leach into the water. This corrosion control measure is a preventative step to reduce lead exposure from both service lines and household plumbing.
For customers who are waiting for a service line replacement, or who live in homes built before 1951, Denver Water provides free water pitchers and certified filters to use for drinking and cooking. Residents concerned about lead exposure from their internal plumbing can flush their taps for a few minutes after the water has been sitting unused for several hours. This action clears out any water that may have come into contact with older fixtures or solder.