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Is Denver Tap Water Safe to Drink in 2023?

Scott Winfield
Written by Scott Winfield
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Tap water in Denver is compliant with the US Environmental Protection Agency (EPA) guidelines for healthy drinking water. Denver also consistently ranks as a city with some of the cleanest water in the United States.

However, this doesn’t mean that the water is entirely free of contaminants. Hazardous contaminants like lead, chromium, haloacetic acids, and barium are all present in Denver’s water, albeit in trace amounts.

Denver Water Quality Report: What’s in the Water?

Although Denver’s tap water is considered safe to drink by the authorities, the 2022 water quality reports show the presence of copper, chromium, nitrate, barium, and fluoride. While the levels of these contaminants are well below the limit set by EPA, still, it’s best to learn what dangers they pose and how to eliminate them.

However, the same report has also found the presence of lead in Denver’s water. Since the EPA asserts that there’s no safe level of lead in drinking water, it should be dealt with. 

Another common concern of Denver residents is the presence of cryptosporidium (crypto) and giardia from byproducts of infected animals in the Rocky Mountain region. However, testing has not found traces of these parasites in the drinking water.

Fortunately, Denver’s drinking water has no trace of other dangerous contaminants like arsenic, mercury, or uranium.

A Table of Contaminants for the Denver Tap Water in 2023

Below is a table that lists the concentrations of the most dangerous contaminants found in Denver’s water and how they fare against the EPA regulations.

Contaminant (ppb)Concentration (on average)EPA standards
Lead4.50
Copper621,300
HAA516.260
TTHMs28.980
Barium342,000
Chromium0.03100
Fluoride6004,000
Nitrate7010,000

Lead and Copper in Denver Water

Reports show that Denver tap water has copper, but its levels are not alarming. There are only 62 parts per billion (ppb) of copper in Denver’s drinking water, which is quite safe considering that the EPA standard is 1,300ppb.

However, the same can’t be said for the lead presence in Denver’s tap water. Denver tap water contains 4.5ppb of lead. As the EPA establishes, there should be no lead in the water (even in trace amounts) as it can cause a plethora of health concerns varying in severity – from stomach issues and constipation to memory loss and nervous system damage. 

We should also note that the lead does not come from the water supply itself. The presence of lead in this city’s water comes from lead pipes and fixtures in older residences and some privately owned properties built prior to 1986.

Buildings constructed before 1986 may have higher traces of lead and copper because these metals were commonly used in the construction of water supply lines. Consider checking the piping, solders, faucets, and fixtures in your residence for corrosion. Fixtures produced before 2014 will likely not meet EPA guidelines (as this is when the EPA started enforcing regulations) and may cause higher lead levels in tap water.

The good news is that Denver authorities are running a Lead Reduction Program to eliminate this issue.

Chromium, Haloacetic Acids, and Total Trihalomethanes

Chromium is another dangerous contaminant that is present in Denver’s tap water. It is a naturally found element that leaches into water. However, sometimes, the presence of chromium in tap water might be a consequence of the discharge by steel and pulp mills that mixes with the surface water.

That being said, EPA considers trace elements up to 100ppb of chromium to be safe, whereas water reports show that, on average, there’s only 0.3ppb of chromium in Denver’s water. Still, as chromium is a highly carcinogenic pollutant, you may want to remove any trace amounts of it from your drinking water.

Other contaminants found in Denver’s tap water that might be a cause for concern are haloacetic acids (HAA5) and total trihalomethanes (TTHMs) – both may be potentially cancerous. HAA5 is naturally found and quite common in public water systems all across the USA and has been linked to bladder cancer, while TTHMs are a byproduct of chlorine, which is a chemical used to sanitize public water systems.

However, just like chromium, these contaminants fall within the legal limit set by the EPA, too. The EPA standard for HAA5 is 60ppb, while there’s only 16.2ppb of HAA5 in the Denver water. The reported TTHMs levels aren’t worrying either, as the 28.9ppb amount is safely below the 80ppb standard set by the EPA.

Nitrate, Barium, and Fluoride

Nitrate, barium, and fluoride can be found anywhere on Earth in natural deposits, and when these deposits erode over time, they can easily leach into the surface water. That’s the case in Denver, too.

In addition to natural erosion, nitrate can find its way to the water supply through runoff from septic tanks and systems, while barium can sneak into water sources via drilling waste. Fluoride, on the other hand, is intentionally added into drinking water to help protect teeth health, but it may also end up in the water because of improper waste dumps from aluminum and fertilizer factories.

If the levels of these elements in drinking water are too high, they become a serious health concern. Nitrate is well-known as a quite powerful poison. Barium, when consumed in large doses, can cause paralysis and even death. High levels of fluoride in drinking water can result in arthritis.

That being said, Denver residents have nothing to fear about any of these contaminants as they’re fairly below the EPA’s safe thresholds.

Is Denver Tap Water Hard or Soft?

Denver’s tap water is classified as “soft to moderately hard.”

Hardness in water is caused by compounds of calcium, magnesium, and other mineral sediments. The USGS classifies soft water as anything below 60 milligrams of metals per litre and hard water as anything between 121 to 180mg/L.

Denver Water, the largest water treatment center in Denver, has two collection points. The southern collection point is listed as “moderately hard,” with 75 to 120mg/L. Its northern collection point is listed as “soft” water and measures 40 to 50mg/L.

Because Denver’s tap water is sourced entirely from surface water, it tends to be softer than groundwater. The quick movement of surface water usually prevents most minerals from dissolving into the water.

However, surface water may become “harder” in winter, as waterways and reservoirs freeze and allow the water to absorb more minerals.

While there are no health risks to consuming hard water, it can be a source of inconvenience. You may notice chalky residue on cleaned dishes, difficulty in creating suds when washing your hair and hands, as well as a slight mineral aftertaste.

If you’re unsure about your water hardness level, we recommend you to send your water sample to a certified water testing lab like Simplelab Technologies.

Where Does Denver Get Its Water?

Denver’s water is 100% sourced from surface water. Surface water is water from snowmelt that has accumulated in rivers, streams, creeks, lakes, and reservoirs.

The primary source of Denver’s surface water is the Rocky Mountains.

This water then passes through three primary filtration and treatment plants that serve the residents of Denver and some surrounding suburbs The three filtration and treatment plants include the Denver Water Board (1.4 million residents), the North Washington Street Water & Sanitation District (34,000 residents), and the Crestview WSD (18,000 residents).

Surface water from the Rocky Mountains travels along the Colorado River to residents as far south as southern California. Denver is the first and closest stop. This allows the city to collect the water that comes from freshly melted snow before it travels across the ground and picks up added sediment and contaminants.

As a result, Denver has some of the freshest and cleanest water, even before the filtration and disinfection processes.

How is Tap Water Treated in Denver?

Although water from the Rocky Mountains is generally clean, all water is filtered through treatment centers before it is distributed to homes and businesses.

The Denver Water Board has explained the process in detail:

  1. Coagulation or flocculation: In this first step, the “raw,” untreated water is collected in large basins. Alum, a non-toxic liquid, and polymer substances are added into the water and cause solid sediments to stick together in large clumps.
Coagulation or flocculation
Coagulation or flocculation
  1. Sedimentation: As they grow larger, these clumps grow heavier and sink to the bottom of the basin. Once they do, these fragments get separated from the water.
sedimentation
sedimentation
  1. Filtration: The water is then filtered through fine layers of granulated materials to remove any smaller particles remaining in the water. Depending on the treatment center, these layers are made of either sand or coal. The result is clear, sediment-free water.
Filtration
Filtration
  1. Disinfection: After the sediment has been removed, a disinfectant is added to the water to treat bacteria, viruses, and any other remaining microbes.
Disinfection
Disinfection
  1. Corrosion control: Overly acidic water may react with the metal distribution systems and plumbing. Alkaline substances are added to the water to maintain a pH to reduce corrosion as the water moves.
Corrosion control
Corrosion control
  1. Distribution: Finally, the water is sent underground to reservoirs and through the distribution systems. These lead the water to homes and businesses.
Distribution
Distribution

Does Denver Have the Cleanest Tap Water?

Denver is considered one of the cities with the cleanest water in the United States. While there is much contention over which city takes first place, Denver is consistently listed at the top.

Cities that regularly compete with Denver for cleanest (and best-tasting) tap water are Louisville, Kentucky (with water filtered from the Ohio River), and New York City, with water from reservoirs in the Catskill Mountains.

Chicago tap water is also one of the cleanest.

Do People Drink Tap Water in Denver?

Residents regularly drink Denver’s tap water. However, water filters for pitchers and faucets (along with home filtration systems) are growing in popularity.

These filters are used to remove any contaminants that might have entered your tap water en route from the water treatment center to your home. Depending on the type of filter, they can remove chlorine, unwanted minerals, bacteria, and even lead.

Conclusion

Denver’s tap water is safe to drink since all the hazardous contaminants are well below the health standards set by the EPA. The only exception is lead that leaches into the drinking water via eroding old pipes, solders, and fixtures.

To eliminate the potential health risks caused by this dangerous heavy metal, you may want to consider installing water filters or purchasing water pitchers that can effectively remove it.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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