Current Issue
Photo: Getty Images.

Do You Know What’s in Your Water?

We dug into Colorado’s public water to give you the facts you need to know.

You bathe, wash dishes and clothes, cook dinner, and fill water bottles from the tap. But what do you know about the water in your home? How is it treated? Is it free of contaminants? What can you do to help protect the water supply?

Colorado is a headwaters state, meaning that most of its rivers start right here in the Rocky Mountains. And all that fresh water in Colorado’s rivers and streams, in addition to the snow falling in the mountains, supplies our state with its drinking water. The snow melts, then the water is brought to treatment facilities to be cleaned and delivered to your family’s home.

There are many factors that influence the quality of this water—minerals and metals in the soil, bacteria from wildlife, pollution run-off, and industrial waste being major contributors to contamination, according to Jayla Poppleton, executive director at Water Education Colorado. 

“We’re fortunate here in the Denver metro area as our drinking water is 100% surface water that comes from rivers, streams, and reservoirs fed by high-quality mountain snow,” says Travis Thompson, communications manager at Denver Water. “Because of this, our water does not pass through a lot of development, agriculture or industry before entering our watersheds. This means the risk of substances in the water coming down our mountains before being treated at our plants is much lower than other areas in the U.S.”

The Environmental Protection Agency (EPA) oversees drinking water regulations with legal allowable limits for a list of more than 90 contaminants that all states must follow, with more added periodically. The EPA sets these levels based on the type of contaminant, their supposed adverse health effects, and chance of occurrence in public water supplies. They also have a list of health advisories—that are merely suggestions and not legally enforceable—for additional contaminants, such as manganese, which can be natural or due to industries like mining, and per- and polyfluoroalkyl substances known as PFAS, a group of manufactured chemicals. 

According to Thompson, Denver Water regularly tests water at points along the way, from the mountains to spots around the city. In 2021 Denver Water collected more than 55,000 water samples and conducted more than 200,000 tests. “Denver Water has its own laboratory and team of scientists who work hard to ensure we know what’s in the water before it makes it to our treatment plants. These scientists also ensure that the water we are cleaning at these plants and distributing to customers goes above and beyond state and federal drinking water regulations.” says Thompson. 

Public water can have low or undetectable levels of elemental or chemical impurities like metals, pharmaceuticals, household products, disinfectant byproducts, PFAS, and hardness, says Katherine James, Ph.D., an associate professor at the Center for Health, Work, & Environment at the Colorado School of Public Health. “Because of the sanitation processes in place, it is very rare to see high levels of these contaminants in drinking water,” she says. It is important to note that if you have private well water, the homeowner is responsible for the testing and treatment of that water.

If you look up your zip code on the Environmental Working Group (EWG) Tap Water Database and see a list of contaminants your water contains, it may give you pause. These are either within the allowable limits by the EPA, or are not currently a known cause for concern. And before you permanently switch to bottled water, understand that most bottled water companies also use tap water as their source. Bottled water is monitored by the Food & Drug Administration—using EPA regulations—and is not required to disclose water quality information. “In general, water from public water supply is safe,” James says. 

In saying that, here’s what you can do to keep your family healthy, as well as sustainable ways to improve quality without resorting to disposable plastic. 

Toxins & Pregnancy 

For every contaminant that crosses the placental barrier, there is a chance it could have immediate or long term impacts on the baby and mother. According to a 2019 Systematic Review of Environmental Contaminants Exposure and Preterm Birth published in the peer-reviewed journal Toxics, toxic metals are one of the biggest known sources of concern, with a correlation found between lead, mercury, cadmium, and arsenic and preterm delivery, placental hemorrhage, and stunted fetal growth and development. This review also found that disinfection byproducts and atrazine (a type of herbicide that ends up in the water from irrigation runoff) may have links to preterm birth, but the association is unclear. 

Before you worry, first understand that “these impacts are dependent on both dosage and the relevant window of exposure for fetal development,” says James. Research is still investigating the adverse effects of low-level contaminants from drinking water, however there is little conclusive evidence that drinking water supplied from public water sources is negatively linked to birth and pregnancy outcomes, James says. Plus, studies have already shown the significance of water consumption during pregnancy and postpartum for the health of the mother and child. The American College of Obstetricians and Gynecologists recommends eight to 12 cups of water per day.

The Effect on Child Development 

Any contaminant—natural or man made—has the possibility of having harmful effects on kids.  Children tend to take in more water relative to their body size than adults do, therefore could have higher exposure to drinking water contaminants, according to the EPA.

“This is more concerning for those under the age of five, when rapid physical growth occurs, or ages nine to 13, when chemical changes occur during puberty,” James explains. “Some contaminants (heavy metals, pesticides, and PFAS) at elevated levels are associated with long term risk for adverse health outcomes; however, conclusions about the biological relevant dose or how the contaminants interact with each other in water is still unknown.” Water is an important part of a child’s diet, so rather than switch to juice or bottled water, use tap and mitigate your risks through filtering, says James. 

Get the Lead Out 

Unlike other contaminants, lead has a maximum contaminant level goal of zero in drinking water. Lead can be passed from mom to baby and damage their nervous system, so it is especially dangerous during pregnancy. Exposure to lead via drinking water may be particularly high among babies who consume formula prepared with lead-contaminated water. The National Toxicology Program has concluded that childhood lead exposure is associated with reduced cognitive function, reduced academic achievement, and increased attention-related behavioral problems.

Some water lines in Colorado are still lead-lined, which when corroded, leach traces of lead into already-treated public water, says Poppleton of Water Education Colorado. The service lines that bring water from the main line into the home are the responsibility of the homeowner and can cost anywhere from $5,000 to $10,000 to replace. To help with the cost, there is a Lead Service Line Replacement Project in Denver that aims to fix the affected homes by replacing lead lines with copper lines by 2035. Visit for more information on the process and to request a free lead testing kit. 

The 411 on PFAS

The latest contaminant concerns are a group of manufactured chemicals, called per- and polyfluoroalkyl substances or PFAS, for short. There are thousands of PFAS, however a common characteristic is that they break down slowly and build-up over time in people, animals, and the environment. Current research suggests high exposure to PFAS leads to decreased fertility or increased high blood pressure in pregnant women, developmental effects or delays in children, including low birth weight, accelerated puberty, bone variations, or behavioral changes, and an increased risk of some cancers. More studies need to be conducted to better understand the effects and the impacts at lower levels of exposure. 

In Colorado, one of the biggest causes of PFAS ending up in the water is due to urban and wild fires, since the firefighting foam contains chemicals, says Poppleton. And when the foam is left on the ground, it can sink into the soil and groundwater or run-off into rivers and streams, Poppleton explains. The EPA released a health advisory for PFOA and PFOS at 70 parts per trillion. “If testing reveals elevated levels of PFAS in a utility’s water supply, the water provider may respond by making water stations available or diverting water from another source. A longer term solution is to improve treatment plants to remove the PFAS,” Poppleton says.

If you are concerned about PFAS exposure, test your water with an at-home kit and consider installing a reverse osmosis filtration system.

Protect Your Water

Water is one of the most important resources to sustain life and is crucial to the landscape in Colorado. Here’s how you can do your part to keep it clean, drinkable, and available for future generations, according to Water Education Colorado. 

Filter Options

Remove more contaminants from the water you drink with one of these filters.

Family Food

Newsletter Signup

Your weekly guide to Mile High family fun. Colorado Parent has a newsletter for every parent. Sign Up