Frequently Asked Questions about Water Quality

  • Is Denver's tap water safe to drink?

    Yes, our water more than meets all regulatory mandates and never has violated any standard. Drinking water is regulated through the Colorado Department of Public Health and Environment and the Environmental Protection Agency.

  • Is there lead in my water, and if so what can I do about it?

    Denver Water has not detected lead in its treated water or source water. However, lead can come from a customer's plumbing and/or service line. If you are concerned about lead in your drinking water, you can request a lead test from Denver Water.

    There are also several things you can do to reduce the risk of exposure to lead from tap water.

  • 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 it okay 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.

  • 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.

  • 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 protected 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.

  • Can toxic spills that seep into the ground or groundwater contaminate my drinking water?

    It is highly unlikely that toxic spills in the ground or groundwater could contaminate the drinking water since the treated water system is enclosed. See Question 3 for more information.

  • Why don't you allow recreation on some of your reservoirs?

    Three of our reservoirs are "terminal reservoirs," meaning they are the last storage points of water before treatment. We do not allow recreation on these reservoirs. This protects the water from potential contamination prior to treatment. A cleaner source helps yield a cleaner product.

  • What makes my water smell/taste bad?

    Water can pick up tastes and odors from new pipe, from low usage in the treated water system or from natural elements in the source water. Taste and odor events often occur seasonally during blooms of algae or aquatic plants. Although the plant material is removed during treatment, sometimes the odors persist. Tastes and odors in treated water are not harmful, but we do take steps to try and eliminate them.

  • Why is the water discolored?

    The discoloration is usually rust from aging pipes. It is not harmful, but is aesthetically displeasing. Discoloration of the water can be a result of disturbances in the water line due to using a hydrant improperly, installing new pipe, or shutting off the water to a local area for system maintenance. Home plumbing can also cause discoloration of the water.

  • 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.

  • What about waterborne parasites like Cryptosporidium and Giardia?

    Denver Water has tested for these parasites in the water for over a decade. Both organisms are found in source water, but not in the treated water. We add sufficient amounts of disinfectant during the treatment process to inactivate Giardia and other organisms. Effective filtration also helps remove both parasites. This is part of the federal governments Surface Water Treatment Rule (SWTR). We are required to add a certain amount of disinfectant for a specific amount of time to satisfy this requirement.

  • Why does my skin itch after I shower 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.

  • How will water hardness affect my detergent, iron or humidifier?

    Most customers who call about hardness are inquiring for detergent usage amounts, or for adding tap water to their irons or humidifiers. The units of measurement for most appliances are in grains per gallon, but we measure in milligrams per liter.

    Harder water will form a mineral scale on plumbing. This is purely aesthetic and does not impact the safety or health of the water. Water hardness is a result of calcium and magnesium salts dissolved in water. High concentrations of these minerals make water hard. The South Platte source water is considered moderately hard. At times, it is greater than 5.8 grains per gallon or 100 milligrams per liter, and it varies seasonally between 4 to 7 grains per gallon of hardness. The Moffat source is softer, and varies seasonally between 1 to 3 grains per gallon. Many cities across the nation have much harder water than Denver’s.

  • How do I treat the water for my fish?

    Always use a dechlorinating agent for chloramine.

  • Denver Water asks us to conserve the water, yet I see your crews wasting water, by flushing hydrants. Why do you do that?

    Even the best water will get stale and taste unpleasant if not used sufficiently. Conservation is important, but to maintain good, fresh water, flushing is vital, especially in areas where water usage is low.

If you have a question that is not answered here please call 303-893-2444 (regular business hours: Monday – Friday, 7:30 a.m. – 5:30 p.m.) or send an email (please allow up to two business days for a reply).