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Water Quality FAQs

Do I need a water filter?

Your tap water is perfectly safe without one. If you have an internal problem with your plumbing or your home has a lead service line or plumbing that contains lead, you may want to consider a filter or treatment system.

Is bottled water safer than tap water?

Many bottled water companies use tap water as the source. Currently, bottled water is not as heavily regulated or tested as tap water. Instead bottled water is regulated through the Food and Drug Administration and is considered a food product. Additionally, water utilities are required to release information on their water's quality and bottled water companies are not.

Is it safe to drink hot water from the tap?

No, never drink or use hot water from the tap for consumption or food or beverage preparation. Hot water systems (tanks, boilers) contain metallic parts that corrode over time and contaminate the hot water.

How long can tap water be stored, and how should it be stored?

Cold tap water can be stored for about two weeks if kept sealed, away from light and cold or at least cooled, in a clean, amber or foil-covered glass or hard plastic container.

Where does our water come from?

The sources of Denver's water are primarily runoff from snowmelt high in the Rocky Mountains. The portion of the South Platte River that runs through the metro area is not a source for Denver Water.

Is the water safe from contamination?

Denver Water has caretakers overseeing its source water, but our watershed is very large and potentially toxic spills or acts of nature, though rare, are possible. When a spill occurs we work with the local authorities and regulatory agencies to remedy the situation before it becomes a problem.

Also, it is highly unlikely that toxic spills in the ground or groundwater could contaminate the drinking water since the treated water system is enclosed.

What chemicals do you put in the water?

During the treatment process aluminum sulfate (alum) and polymer are added to the untreated water. These chemicals bind with foreign matter such as dirt particles and form into large clumps that can be removed during the sedimentation and filtration portion of the treatment. After filtration, fluoride is added as needed to achieve fluoridation guidelines set by the state health department. Finally a disinfectant is added to protect the drinking water from potentially harmful microscopic organisms. All chemicals that are added are certified food grade (safe for use in foods).

Other chemicals added include potassium permanganate, carbon dioxide, lime, caustic soda and fluoride containing compounds. All of the chemicals are certified as food grade or to meet ANSI/NSF 60 Standards for Drinking Water Additives and they meet AWWA standards.

What is in Denver's treated water?

All natural waters contain minerals and some chemicals. The EPA has identified more than 80 potential contaminants that when present at levels above established limits (Maximum Contaminant Level or MCL) may be a health threat. For more information please view the latest Water Quality Report.

Why does my skin itch after showering in the winter?

Our climate is usually cold and dry during the winter, and we tend to take hotter showers because of it. However, hot water dries the skin. Taking a warm shower instead of a hot one should help.

Why does the water appear blue/green when I fill my white bathtub?

Treated tap water is nearly colorless, and — similar to a clear crystal or raindrops reflecting light to create rainbows — the water in your bathtub can absorb and reflect the different wavelengths in the light we see. A blue or green tint in your bathtub water is typically the result of wavelengths of light from the lightbulbs in the bathroom being absorbed and reflected by the water in the tub. The more water there is in the tub the more noticeable the tint may be. Also, different types of light bulbs can make the water appear different colors.

A less likely scenario is that blue- or green-colored water could be caused by particles from the anode rod in your home's water heater degrading, as it’s designed to do. The anode rod, which protects your water heater from corrosion, is made of metals including aluminum, which can form a green gelatinous material as it degrades. These particles may be especially apparent when draining the water heater. 

Bottom line: A green or blue tint to the water in a white bathtub is completely normal. More color may be seen depending on the kind of lightbulbs in your bathroom and the depth of water in the tub. Denver Water routinely tests its water throughout the distribution system, collecting thousands of samples and conducting thousands of tests every year. 

One good test you can do at home is to fill a clean, clear glass with cold water from the tap and hold it up to a light or the sunshine to see if the water has any color.
 

How can I request water quality related data?

You can initiate a request for water quality related data from the DW GIS Maps and Data Request page. After you register, you can request Watershed/Collection Sampling Locations, Watershed/Collection Testing Data, Distribution System Sampling Locations, and Testing Data, as well as Additional Water Quality Data. DW staff will review the request and contact you.

To know more about how Denver Water is managing water quality from source to tap, open this story map.

How do I treat the water for my fish?

Always use a dechlorinating agent for chloramine.