Denver Water Quality Analysis

Who Regulates Denver’s Drinking Water?

Serving 1.5 million thirsty folks is a team effort. 

Several organizations work together to tackle the task, including:

• The Environmental Protection Agency (EPA) enforces limits on over 120 different contaminants in public water systems. 
• The Food and Drug Administration (FDA) sets limits for contaminants in bottled water.
• The Colorado Department of Public Health and Environment (CDPHE) regulates the amount of certain contaminants allowed in Denver’s tap water.  
• Denver Water is the organization in charge of treating, monitoring and testing the city’s source water and treatment plants.

Here’s what Denver Water found in their latest water quality report:

Denver Water’s Annual Water Quality Report

Denver Water’s 2021 Water Quality Report met all requirements set by the EPA and state health department.

The report is based on data from dozens of sites monitored across the distribution system.  

Only once, way back in 2012, did they find any serious issues. Since then they’ve passed with flying colors!

When it comes to disease-causing pathogens, they haven’t found any since testing began in 1980. Yippee!

The city also tests for several unregulated contaminants, like microplastics and per-fluoralkyl substances (PFAS). They didn’t find any of those as well. 

With that said, not everyone agrees with Denver Water’s squeaky clean report...

Environmental Working Group’s Water Quality Report 

The Environmental Working Group (EWG) is a non-profit organization that publishes their own comprehensive water quality reports.

They use data from the Colorado Department of Public Health & Environment and the US EPA Enforcement and Compliance History database (ECHO).

Overall, the EWG’s health standards are a lot stricter than the federal government’s. 

In their latest report, the EWG found 10 cancer-causing contaminants above healthy limits, including:

• Arsenic: 22x EWG HEALTH GUIDELINES
• Bromodichloromethane: 114x EWG HEALTH GUIDELINES
• Chloroform: 32x EWG HEALTH GUIDELINES
• Dibromoacetic acid: 5.4x EWG HEALTH GUIDELINES
• Dibromochloromethane: 21x EWG HEALTH GUIDELINES
• Dichloroacetic acid: 43x EWG HEALTH GUIDELINES
• Haloacetic acids: 149x EWG HEALTH GUIDELINES
• Radium: 6.7x EWG HEALTH GUIDELINES
• Total trihalomethanes: 160x EWG HEALTH GUIDELINES
• Trichloroacetic acid: 43x EWG HEALTH GUIDELINES

Although these substances are not regulated by the EPA, lab tests show that they can still have negative side effects on living organisms.

So which report should you listen to? Denver Water’s or the EWG?

Ultimately, it’s up to you to decide which guidelines to follow. 

If you want to play it safe, you can always install an in-home water filter, but more on that later…

For now, let’s take a look at where Denver gets its source water:

Where Does Denver Get Its Water?

Denver’s drinking water comes from the South Platte River and its tributaries, as well as the streams and canals that feed the Dillon Reservoir and Fraser River. 

It starts as mountain snow runoff before flowing through 3,000 square miles of watersheds. 

Denver stores its water in five mountain reservoirs:

1. Antero
2. Eleven Mile Canyon
3. Cheesman
4. Dillon 
5. Gross

From there, it travels to the city for treatment.

Treating Denver’s Drinking Water

Denver Water’s three treatment plants remove the contaminants and microorganisms found in raw water. 

After filtration, the water is disinfected with chloramines, a chemical that destroys potentially harmful pathogens. 

Chloramines are a healthier alternative to chlorine that produces fewer toxic byproducts, but more on that in a sec…

First, here’s a quick breakdown of the treatment process in action:

1. Coagulation & Flocculation: A process that adds alum and polymer to clump together small particles so they can be easily removed. 
2. Sedimentation: The clumped particles settle at the bottom of the tank, and the clearer water on top passes through. 
3. Filtration: The water filters through layers of sand and activated charcoal. 
4. Disinfection: Chloramine disinfects the water of bacteria, viruses and parasites. 
5. Fluoridation: Fluoride is added to prevent cavities. 
6. Corrosion control: Alkaline substances are added to balance the water’s pH and reduce corrosion in distribution pipes.

After treatment, the water is stored in underground, clean-water reservoirs before continuing to your home or business.

Testing and Monitoring Denver’s Water

Denver Water performs thousands of water quality tests a year. 

In 2020 alone, they collected more than 35,000 water samples and conducted 70,000 tests for contaminants. 

While Denver Water monitors the treatment process, The Colorado Department of Public Health and Environment monitors the city’s source water in lakes and rivers.  

They also conduct an annual evaluation of Denver's three main reservoirs: Strontia Springs, Marston and Ralston (the last stop before treatment).

Contaminants Threatening Denver’s Water Supply

Despite the city’s best efforts to keep drinking water toxin-free, it’s normal for a small amount of contaminants to sneak through. 

This doesn’t necessarily pose an immediate health threat, but it’s something to be aware of. 

Common contaminants to lookout for include:

• Viruses, bacteria and parasites from septic tanks, livestock operations and sewage plants
• Pesticides and herbicides from agriculture and residential uses
• Salts, metals and other byproducts from industrial waste, mining, farming, urban stormwater and oil and gas production
• Radioactive contaminants from oil, gas and mining operations, as well as some that occur naturally in the rocks and soil

Out of all the potential pollutants, pathogens like viruses, bacteria and parasites are at the top of the watch list.  

Next, let’s take a closer look at the risk of pathogens in Denver’s tap water:

Should You Be Worried About Bacteria, Parasites and Viruses?

A boatload of microorganisms make their homes in local lakes, reservoirs and streams, but Cryptosporidium (Crypto), Giardia and Cyanobacteria are the most common. 

They enter Denver’s water through animal waste in watersheds. 

Denver Water tests for Crypto and Giardia in both raw and treated water. 

When ingested, they can cause fever, cramps, diarrhea and other gastrointestinal symptoms. 

Fortunately, Denver Water has never detected Crypto or Giardia in their treated water. 

Cyanobacteria is a type of blue-green algae that produces harmful compounds called cyanotoxins. 

They can cause health effects like gastrointestinal discomfort, liver inflammation and skin rashes. 

Denver Water continuously monitors for Cyanobacteria and they can easily switch between water sources if they ever find them. 

To date, Denver Water has never detected Cyanobacteria in it’s water.

The City’s Steps to Reduce Lead Exposure

Lead service lines were common until 1951 and lead pipes were installed in homes through 1986.

Lead is a toxic heavy metal that can cause side effects like heart disease, cancer and learning difficulties in children. 

When the water leaves the treatment plant it’s lead-free, but there is a catch:

Lead can still enter the water from lead parts in household plumbing and water service lines. 

That’s why the city started its Lead Reduction Program, a 15-year project to replace over 64,000 lead service lines throughout the city. 

The Lead Reduction Program has four main missions:

1. Increase the water’s pH to prevent lead leaching from pipes. 
2. Replace all government-owned lead service lines.
3. Develop a public database of customer-owned lead service lines. 
4. Remove all lead service lines by 2035.
5. Provide free home water filters to all residents who have a lead service line until their line is replaced.

In the meantime, there’s plenty you can do at home to minimize the risk of lead exposure... 

What Can You Do to Protect Your Family from Lead Exposure?

Here’s a few tips to protect your family from lead:

• Run your water for five minutes if it hasn’t been used in a few hours. 
• Only use cold water for drinking and cooking.
• Replace old faucets and fixtures with lead-free ones. Faucets and fixtures installed before 2014 do not meet today’s requirements for “lead-free”.
• Remove and clean faucet screens (aerators). Old screens can trap lead particles that leach from lead service lines. 
• Install an NSF-certified water filter in your home

Water filters are by far the most effective way to protect your family from lead, but they need to be properly maintained. 

That means regularly replacing filtration cartridges and membranes! 

Disinfection Byproducts In Denver’s Drinking Water

All treated water contains some level of disinfection byproducts, or DBPs. 

DBPs are created when chemicals like chlorine and chloramine interact with organic matter in water. 

Studies show that they’re pretty awful for human health, with side effects like bladder cancer. 

Yikes!

Denver Water uses chloramine instead of chlorine, which produces fewer DBPs, but it’s still a risk.

Unfortunately, DBPs are a necessary evil because chemical disinfectants are the only way to effectively kill pathogens in large volumes of water. 

At home, however, you have several healthier options for disinfecting your water…

Ultraviolet treatment systems deactivate harmful pathogens with UV light.

Reverse osmosis (RO) systems, on the other hand, remove bacteria, viruses and up to 99.9% of all contaminants, but more on that later…

For now, let’s talk about that smell:

Does Denver’s Water Stink?

Water easily picks up bad tastes and odors because it’s a universal solvent. 

Most of the time Denver’s water smells fine, but during the height of summer and beginning of fall, rapid temperature changes can lead to an unusual taste or smell. 

This happens when dissolved compounds release from microorganisms like plankton and algae. 

Although they aren’t harmful to human health, they do stink!

In order to control the smell, Denver Water adds powder activated carbon to the treatment process. 

At home, you can take matters into your own hands by installing an activated carbon filter of your own. 

You can choose between water pitcher filters, faucet filters, or go all-out and with an RO filtration system. 

Just remember to regularly replace those filtration cartridges!

How Hard Is Denver’s Tap Water?

Hardness/softness refers to the amount of minerals dissolved in the water. 

Hard water contains large amounts of calcium and magnesium. 

If your water leaves filmy stains in the sink and shower, it could be a sign of hard water. 

Soap that doesn’t sud is another common sign. 

Extremely hard water can also leave a chalky aftertaste. 

Denver’s water is slightly harder in the winter when the lakes freeze and softer in the late spring and fall when they melt. 

At home, you can install a water softener to remove excess minerals. 

An RO system will also do the trick (they take care of just about everything).

Should Denver Residents Use In-Home Water Filters?

The city of Denver does all it can to provide clean drinking water, but they can only do so much... 

As you now know, issues like lead exposure, disinfection byproducts, hardness and smell are an ongoing concern. 

The best way to protect your family is to install an RO filtration system.

They combine sediment filters, activated carbon filters, ion exchange resins, RO membranes and polishing filters to remove lead, disinfection byproducts, bacteria and up to 99.9% of all harmful contaminants.  

High-end RO systems even use remineralization to add the perfect amount of healthy minerals back into the water. 

Cloud Water Filters also use built-in software to monitor your water quality 24/7. 

Your tap water will be clean, safe and best of all, delicious!

Click here to learn more.