Is Colorado Tap Water Safe to Drink? What You Need to Know

Colorado is home to some of the most celebrated water sources in the country. Snowmelt from the Rocky Mountains feeds reservoirs and rivers that supply millions of residents across the Front Range and beyond. Municipal water utilities throughout the state treat this water to meet or exceed federal drinking water standards before it reaches your home. But the question "Is my tap water safe?" is more nuanced than a simple yes or no. Here is what Colorado residents should understand about their tap water.

How Colorado Municipal Water Is Treated

Every public water system in Colorado is required to follow treatment protocols established by the U.S. Environmental Protection Agency (EPA) under the Safe Drinking Water Act. These protocols involve multiple stages designed to remove or reduce contaminants before water enters the distribution system.

The typical treatment process begins with coagulation and flocculation, where chemicals are added to bind with suspended particles so they can be removed. The water then passes through sedimentation basins where heavier particles settle, followed by filtration through sand, gravel, or activated carbon to capture remaining particulates. Finally, disinfection -- usually with chlorine or chloramine -- eliminates bacteria, viruses, and other microorganisms.

Major utilities like Denver Water, Aurora Water, and Colorado Springs Utilities publish annual Consumer Confidence Reports (also called Water Quality Reports) that detail the results of thousands of tests conducted throughout the year. These reports are publicly available and provide a snapshot of what was detected in the treated water supply.

What the EPA Regulates -- and What It Does Not

The EPA currently regulates over 90 contaminants in public drinking water, setting enforceable Maximum Contaminant Levels (MCLs) for substances such as lead, arsenic, nitrates, and disinfection byproducts. These standards represent the legal limits that public water systems must meet.

However, there are hundreds of other substances that are not currently regulated under federal law. The EPA maintains a Contaminant Candidate List (CCL) of chemicals and microorganisms that are known or anticipated to occur in public water systems but do not yet have enforceable standards. Emerging contaminants such as per- and polyfluoroalkyl substances (PFAS), pharmaceutical residues, and microplastics fall into this category.

In 2024, the EPA finalized the first-ever national drinking water standard for several PFAS compounds, marking a significant step toward regulating these persistent chemicals. Colorado has been proactive in monitoring PFAS levels, particularly in communities near military installations and industrial sites where these compounds have been detected in groundwater.

The Journey from Treatment Plant to Your Tap

Even when water leaves the treatment plant in compliance with all federal and state standards, it still has to travel through miles of underground distribution mains, a service line connecting the main to your home, and your home's internal plumbing before it reaches your faucet.

Each stage of this journey introduces variables. Aging distribution pipes can contribute trace metals or sediment. Service lines made of lead, galvanized steel, or other older materials may affect water quality at the point of entry. Inside the home, the type and age of your plumbing -- copper, galvanized steel, PEX, or a combination -- determines how water interacts with your pipes before reaching the tap.

Water that sits in pipes overnight or during periods of low use can accumulate higher concentrations of dissolved metals and lose residual disinfectant, which is why first-draw water (the first water out of the tap in the morning) can differ from water that has been running for several seconds.

Local Considerations for Colorado Residents

Colorado's geography and climate create some region-specific water quality considerations. Much of the state's water originates as snowmelt, which is naturally soft and low in minerals. However, as water is transported, stored, and treated, its mineral content can change. Communities on the Eastern Plains that rely on groundwater sources often have harder water with higher concentrations of calcium and magnesium.

Wildfire activity, which has increased in recent years, can also affect source water quality. Ash and debris from burned watersheds can introduce elevated levels of manganese, dissolved organic carbon, and sediment into reservoirs, requiring utilities to adjust their treatment processes.

Additionally, Colorado's rapid population growth has led to significant infrastructure expansion. New developments are connected to modern distribution systems, while older neighborhoods may rely on infrastructure that is decades old. This means water quality at the tap can vary meaningfully even within the same city, depending on the age and condition of the local infrastructure.

What You Can Do

Understanding your water starts with information. Read your utility's annual water quality report to learn what is being detected at the treatment level. Consider the age and material of your home's plumbing, as this directly influences what reaches your tap. If you want a more complete picture, a home water analysis can measure parameters like hardness, pH, chlorine levels, TDS, and the presence of specific metals at your actual point of use.

Running your cold water tap for 30 seconds to two minutes before drinking or cooking -- especially first thing in the morning -- is a simple practice that flushes stagnant water from your pipes. This is particularly relevant for homes with older plumbing or lead service lines.

Colorado's tap water meets federal safety standards, and the state's utilities work diligently to deliver clean water. At the same time, the last mile -- from the distribution system to your individual tap -- is a variable that only you can evaluate. Awareness is the first step toward clarity.

Disclaimer: The Water Awareness Foundation is an independent educational organization. We are not affiliated with any government agency, water utility, or regulatory body. The information in this article is for educational purposes only and should not be interpreted as medical or legal advice.