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Drinking Water Quality


Boulder has been implementing a comprehensive water supply quality monitoring program for over 30 years. Water quality samples for testing are routinely collected from creeks and reservoirs throughout the Boulder Reservoir Watershed and the Boulder Creek Watershed. Water quality is also monitored during the drinking water treatment process, and in the city’s water distribution system for operations and compliance with drinking water regulations.












About Your Drinking Water

Water Quality Results

All drinking water, including bottled water, contains substances that do not necessarily pose health risks. The city goes above and beyond regulatory requirements, monitoring for 450+ water quality substances including basic chemistry, nutrients, bacteria, metals, disinfection byproducts, pesticides, pharmaceuticals, personal care products, hormones, and radionuclides. The vast majority of these compounds and chemicals are not detected in drinking water.





Annual Drinking Water Quality Reports

2020 Drinking Water Quality Report pdf
2019 Drinking Water Quality Report pdf
2018 Drinking Water Quality Report pdf
2017 Drinking Water Quality Report pdf
2016 Drinking Water Quality Report pdf
2015 Drinking Water Quality Report pdf
2014 Drinking Water Quality Report pdf


Fluoride is a mineral that is naturally found in air, soil, water, plants and foods. Boulder's water sources contain small amounts of natural fluoride. The city  also adds fluoride to the drinking water to achieve a target level of 0.7 mg/L, which is based on 2015  federal  and  state guidance. The City of Boulder continues to pay close attention to scientific and regulatory developments and, as always, will comply with all regulatory changes.


Why is fluoride added to drinking water?
The City of Boulder has added fluoride since 1969 as part of the water treatment process, when Boulder voters approved a ballot measure to require the addition of fluoride to drinking water to reduce tooth decay. Any changes to the fluoridation ordinance would need to be approved by a community vote. All community members also have the opportunity to discuss fluoride at the City of Boulder's Water Resources Advisory Board meetings.


What are the benefits of adding fluoride to drinking water?
According to the  Centers for Disease Control and Prevention (CDC), fluoridated water strengthens teeth and reduces tooth decay by approximately 25 percent in adults and children. Nearly all public health, dental, and medical organizations and agencies including the CDC, World Health Organization, American Dental Association, American Academy of Pediatrics, and the U.S. Department of Health and Human Services recommend community water fluoridation. The CDC considers drinking water fluoridation one of the ten great public health achievements of the 20th century.

What is the city's process for adding fluoride?
During water treatment, the city adds hydrofluorosilicic acid to increase the amount of fluoride in drinking water to a target level of 0.7 mg/L.

Is there a drinking water standard for fluoride?
The U.S. Environmental Protection Agency (EPA) has set an enforceable drinking water standard for fluoride, also referred to as a Maximum Contaminant Level (MCL) or the maximum amount allowed in water from public water systems. The level of fluoride in Boulder’s drinking water is nearly six times lower than the MCL. Fluoridating drinking water is not required, but is a recommended public health measure. Under the Safe Drinking Water Act, EPA is prohibited from requiring public water systems to add any substances for preventative health care purposes.


Are there health risks associated with excess levels of fluoride in drinking water?
According to the  EPA , exposure to excessive levels of fluoride over a lifetime may increase the likelihood of bone fractures in adults. Children under the age of nine, who are exposed to prolonged and elevated fluoride levels have an increased likelihood of dental cosmetic effects. To protect public health from exposure to excessive levels of fluoride, EPA has established an MCL of 4.0 mg/L, which is nearly six times higher than the amount of fluoride in the city’s drinking water.


Can I use tap water with fluoride to mix infant formula?
The CDC has published a community water fluoridation websitewebsite. According to the CDC, infant formula may be prepared with fluoridated drinking water.

Other Helpful Resources


The water processed by Boulder's two water treatment plants is virtually free of lead and copper. These metals are introduced into drinking water mainly from home plumbing where copper pipes and lead solder are commonly found. This is why in 1986 the EPA banned lead solder in all new home plumbing. Since it has been determined that most lead is leached from solder within five years, the systems identified by the U.S. Environmental Protection Agency (EPA) to be at risk are those built between 1982 and 1987. Therefore, only the Boulder sites built or having plumbing changes within this time span are chosen for the monitoring program. Lead levels measured at these taps throughout Boulder are well below the EPA regulatory Action Level.

What the city is doing to reduce lead

Boulder has implemented a Corrosion Control Program that changes the water chemistry to make the water less corrosive.

Most of Boulder's water comes from snowmelt which is naturally low in minerals. Water with a low mineral content is corrosive to pipes. Corrosion control processes at the water treatment plants reduce the tendency for lead and copper to dissolve out of home plumbing.

Corrosion control processes at the Betasso Water Treatment Plant involve the addition of two substances:

  1. Calcium (using calcium hydroxide from naturally occurring limestone) to adjust mineral content
  2. Carbon dioxide to adjust the pH (acid-base balance) of the water. The result is less corrosive water.

The Boulder Reservoir Water Treatment Plant's water has a higher mineral content which is within the alkalinity and pH range needed for corrosion control to match the Betasso treated water.

Additional benefits of the corrosion control program include an anticipated reduction in the failure rate of both city pipes and residential plumbing and a reduction in the metals that are processed by the Wastewater Treatment Plant.

Industrial and commercial water users may want to note these changes and make adjustments as needed.