Is Denver Water Safe To Drink in 2023? (According To Data)

Keen to learn about Denver’s water quality? Is Denver’s tap water safe to drink, and how does it compare to the water in other cities? Are there any contaminants in Denver’s drinking water that you should know about?

We’ve answered all these questions and more in this Denver drinking water quality and safety guide.

🚰 Can You Drink Denver Tap Water?

Yes, it’s generally safe to drink Denver tap water because it’s filtered and disinfected to remove microorganisms that could make you sick.

Plus, the water treatment plants in Denver must comply with EPA guidelines for water quality and safety.

There are a few trace contaminants found in the city’s drinking water, but these contaminants don’t exceed the EPA’s Maximum Contaminant Levels (MCLs).

However, many experts debate whether or not it’s safe to drink tap water containing even trace amounts of impurities with known health concerns.

For instance, the Environmental Working Group, an independent organization and activist group based in the US, believes that the EPA’s standards for water quality are too low, and has set its own Health Guidelines – 11 of which are exceeded by the contaminants in Denver’s tap water.

It’s important to note that the Guidelines set by the Environmental Working Group essentially mean nothing. Facilities must legally comply with the EPA’s Drinking Water Standards, not the EWG’s Guidelines. However, you may agree with the EWG’s belief that the EPA’s Maximum Contaminant Levels for certain health-harmful contaminants are too lenient.

So, is Denver tap water safe to drink? Yes, according to the EPA standards, but no, according to the EWG guidelines. We’ve looked in more detail at the 11 contaminants breaking EWG guidelines in Denver water later in this guide.

👨‍🔧 Looking for more reading material? You might be interested in this post, which lists the states with the worst quality drinking water.

🗺️ Where Does the Tap Water in Denver Come From?

The tap water in Denver comes from snowmelt from Colorado’s Rocky Mountains range, as well as the South Platte River Basin and tributaries of the Colorado River. The entirety of this water is surface water.

Water is collected in more than 4,000 square miles of foothills and mountains west of Denver, and is treated and delivered to 1.5 million people. The city has a large, diverse water collection system because snow isn’t a 100% reliable water source – it’s impossible to predict where the snow will fall, and how much.

Around 94 billion gallons of surface water are collected by the Denver Water utility every year. This water is processed in several treatment stages, including coagulation, which causes contaminants to clump together and sink to the bottom of the treatment basin, and filtration, which removes fine particles.

This clean water is then disinfected to prevent the formation of microorganisms like bacteria and viruses, and alkaline substances are added to raise pH and reduce corrosion in the water service lines. The water is also fluoridated before being delivered around the distribution system.

📉 Who Regulates Denver Tap Water?

Tap water in Denver is managed by the Denver Water Board and regulated by the Environmental Protection Agency.

Denver Water monitors tens of contaminants in the City’s drinking water supply, adhering to the guidelines outlined in the EPA’s National Primary Drinking Water Regulations.

EPA’s Standards, produced under the Safe Drinking Water Act (SDWA), highlight 6 groups of contaminants that all water facilities in the US, including Denver Water, must monitor and reduce in public drinking water supplies:

• Disinfectants
• Disinfection byproducts
• Radionuclides
• Microorganisms
• Organic chemicals
• Inorganic chemicals

The EPA monitors water treatment facilities to ensure compliance with its regulations. If a water facility exceeds any of the EPA-regulated contaminants in its water supply, the facility will be required to take action against this problem – providing test results as proof of this action.

🧪 Denver Water Quality Report

The most recent Water Quality Report (or Consumer Confidence Report) available for viewing online is the 2022 Report, which contains data collected from January-December 2021.

It’s one of the better reports we’ve seen – the information is clearly presented there are no unexplained abbreviations.

According to the report, none of the detected contaminants present in the treated water violated the EPA’s MCLS. Many contaminants, like arsenic, mercury, selenium, and uranium, were detected on average at a BRL – below reporting level – which is good news for consumers.

Some contaminants were detected in trace amounts (although still lower than the EPA’s MCLs), including barium, chromium, fluoride, nitrate, and nickel.

Note that this water quality report doesn’t account for lead in water that may have entered through lead water service lines. Denver recently introduced the Lead Reduction Program Plan, which aims to replace all lead service lines and control lead corrosion with pH treatment, but this doesn’t prevent lead contamination from customer-owned lead pipes, and many lead pipes currently remain in the City.

We recommend taking a look at the Denver Water Quality Report and familiarizing yourself with the contaminants present and how they compare to national standards.

☣️ Contaminants Found Above Guidelines in Tap Water in Denver

According to the latest Consumer Confidence Report for Denver’s public water supply, no contaminants present in the water exceed the EPA’s legal limit.

So, in this section of the guide, we’ve focused on which contaminants in Denver tap water exceed the more stringent guidelines set by the EWG (which, as a reminder, are simply guidelines and aren’t legally enforceable).

According to the EWG Tap Water Database for Denver, 11 contaminants in water treated by the Denver utility exceed the EWG’s Health Guidelines from January 2021-March 2021.

These contaminants are:

Arsenic

The EWG has set a recommended Health Guideline for arsenic of 0.004 PPB (parts per billion). 0.0273 PPB of this highly toxic contaminant was found in Denver’s drinking water – that’s 6.8x the recommended Health Guideline. However, this is nowhere near the EPA’s official legal limit for arsenic of 10 PPB.

Disinfection Byproducts

Since Denver’s water is, for the most part, naturally clean, the main group of contaminants found in the treated drinking water was disinfection byproducts. These include:

• Bromodichloromethane
• Chloroform
• Dibromoacetic acid
• Dibromochloromethane
• Dichloroacetic acid
• Haloacetic acids (HAA5)†
• Haloacetic acids (HAA9)†
• Total trihalomethanes (TTHMs)†
• Trichloroacetic acid

The most well-known disinfection byproducts of this list are chloroform, haloacetic acids (HAA5)†, haloacetic acids (HAA9)†, and total trihalomethanes (TTHMs)†.

Disinfection byproducts are carcinogenic, meaning that they pose a cancer risk. They’re formed when disinfectants such as chlorine react with organic materials naturally present in the water, and are often more dangerous than the disinfectant itself.

Between 0.260 PPB and 23.0 PPB of disinfection byproducts were detected in Denver’s water – between 6.5x and 246x the EWG’s recommended Health Guideline, depending on the contaminant in question.

Radium

0.33 pCi/L (picoCurie per liter) of radium – a naturally occurring radioactive element that may damage the immune system and increase the risk of cancer when consumed in large quantities – was detected in Denver’s tap water. This is 6.7x the EWG’s recommended Health Guideline of 0.05 pCi/L, but well under the EPA’s legal limit of 5 pCi/L.

🧫 Main Contaminants Found in Denver Tap Water

So, we know which contaminants the EWG thinks are present in dangerous amounts in Denver tap water, but are there any other contaminants present at levels that don’t have human health effects?

According to the EWG Tap Water Database for the City, there are a total of 34 total contaminants detected in Denver’s public water.

These include:

• Antimony – A chemical element that may cause nausea, vomiting, and diarrhea if ingested in very high quantities.
• Barium – A naturally occurring metal most commonly found in well water, which may cause vomiting, muscle weakness, abdominal cramps, and blood pressure changes if consumed in excess, or changes of heart rhythm and paralysis if ingested in very large amounts.
• Cadmium – An extremely toxic heavy metal that gets into water as a result of pollution from items containing cadmium. Even low-level cadmium exposure may cause a decrease in bone density and disrupted bone composition.
• Hexavalent chromium – The most dangerous common form of chromium, also known as chromium-6. Consuming high levels of chromium-6 in water may cause various cancers, liver and kidney damage, and eye irritation.
• Fluoride – Although Denver’s water naturally contains low levels of fluoride, the state also fluoridates its water for dental health benefits. Large amounts of fluoride in drinking water can cause dental fluorosis (which stains the teeth) and a metabolic bone disease called skeletal fluorosis.
• Nitrate and nitrite – Two common forms of nitrogen that often contaminate water supplies due to pollution from municipal wastewater treatment plants and agricultural or urban runoff. In excess, nitrates and nitrites may cause a condition called methemoglobinemia, which hinders the blood’s ability to carry oxygen.
• Selenium – A naturally occurring mineral that may cause hair or fingernail loss and circulation problems if prolonged exposure occurs.
• Uranium – A radioactive heavy metal with carcinogenic effects.

🏢 Denver Drinking Water in Public Places

We know about the tap water quality in Denver, but what about the water you’ll receive in public places, like bars, hotels, and restaurants?

The water in these locations is usually the same tap water that you’d get at home. Restaurants and bars aren’t legally required to provide free tap water to customers – and, in fact, Denver has issues with drought, so most restaurants probably won’t offer you water unless you specifically ask for it.

Hotel rooms also offer free drinking water, although some may use recycled water that isn’t safe for drinking (there should be a warning sign near the faucet if so). If your hotel tap water isn’t accessible or safe to drink, you should still get free water if you ask at the hotel bar or reception.

There are more than 100 water fountains in the City, so it’s worth bringing a reusable water bottle with you rather than buying bottled water.

However, if you do want to buy bottled water, you’ll find plenty at your local grocery store from popular bottled water brands like Dasani, Evian, Pure Life, Smartwater, and Aquafina.

💬 Frequently Asked Questions

Is Denver tap water hard or soft?

The water hardness in Denver varies from region to region. There are two collection points at Denver’s largest water treatment center. The northern collection point has 40 to 50 mg/L water hardness, which is classed as soft water. The southern collection point has 75 to 120 mg/L water hardness, which is classed as moderately hard water. All of Denver’s water is sourced from surface water in mountain reservoirs, which is generally softer than groundwater because its dissolved minerals content is lower.

Is Denver tap water safe to drink?

Yes, according to the latest of Denver’s annual Consumer Confidence reports, the City’s water is safe to drink and doesn’t pose a public health risk. No contaminants in the water were detected above the Maximum Contaminant Levels set by the EPA. However, many Denver water customers choose to treat their water with water filters before drinking because they’d rather not drink even trace amounts of certain health-harmful contaminants.

Why is Denver Water so good?

Denver’s water is sourced from high-quality mountain snow in the Rocky Mountains, which is the main reason why it’s considered better than many other city water supplies in the United States. Even the untreated water in Denver contains low levels of contaminants, and this water doesn’t need extensive treatment to make it safe for drinking. However, there are still trace amounts of contaminants like arsenic, radium, and disinfection byproducts in Denver’s water system.

Does Denver Water have lead?

Yes, some of Denver’s drinking water has lead, a known human carcinogen that is extremely dangerous even in small amounts. However, Denver is currently in the process of replacing all its lead water service lines in an effort to reduce its water lead content. If you live in Denver and you’re concerned about lead in your water, conduct a water test.