Water Quality

Who has the tastiest water in the Rocky Mountains? According to the judges of the taste test at the Rocky Mountain American Water Works Association annual conference, Castle Rock Water has the best water in the region in 2015, and in 2016 we took second place. Various municipalities from a three state region competed for the title of best drinking water based on taste, odor and appearance. Castle Rock Water is proud to provide residents with great tasting and reliable water.

Water appearance

We’re all used to turning on the tap and getting cool, clear water. On rare occasions, we might get discolored water at our homes or businesses. While the causes of this discoloration vary, the water is still usually safe.

Pipeline disruptions that change the flow direction or the velocity of water in piping systems, both the public system and / or private plumbing, can cause discolored water. Examples of these disruptions include:
  • Construction activities that require valves to be operated, water to be turned off temporarily or where new taps and mains connect
  • Dead end water mains that are not used very often but are suddenly used at a high rate
  • Electrical outages that impact system pumps or valves
  • Rapid shut-off of faucets or automatic valves in washing machines
  • Rapidly opening or closing fire hydrants or valves
  • Water main breaks


Sometimes, the interior surfaces of water pipes rust or become coated with minerals. When one of the previous disruptions occurs, small pieces of these natural material found in these pipes can be dislodged, causing discoloration or particles in the water.

Defective or aging plumbing can also lead to discolored water. Pieces of rubber or plastic washers that age and crumble can leave particles in the water. Improperly joined dissimilar materials (such as iron and galvanized, or copper and iron) can accelerate corrosion and turn water red or green for short periods of time when disturbance occurs. Aging pipe can also rust or corrode and then become a potential source of discolored water.


As long as the water has a residual chlorine disinfectant (as Castle Rock Water does), the water should be safe. It can, however, be aesthetically displeasing. Castle Rock Water always checks for disinfectant residual anytime we have a water quality complaint or issue.

What to do

Customers can run the water to flush their system. Typically, this is enough to clear up the water, as the disturbance subsides and the discolored water is flushed out. If the issue does not quickly resolve itself, call 720-733-6000 or email us. We will come to your home or business and work to resolve the issue within a few hours of your call. If the issue is in the distribution system, we will flush fire hydrants in the localized area to remove any discolored water from the system.

While Castle Rock cannot eliminate all of the potential causes of occasional discolored water, we work very hard to minimize them. We are committed to providing you the best and most aesthetically pleasing water possible.

Water treatment

Currently, most of Castle Rock’s water comes from nonrenewable wells - some as deep as 2,000 feet below ground. In the past, chlorine alone was used to disinfect the water. Renewable water sources that are either surface waters or connected to surface waters (e.g. shallow groundwater along Plum Creek), however, can contain natural organic matter which can cause the formation of disinfection byproducts when disinfected only with chlorine. In May 2013, the Town began treating its water with chloramines, which is a product of chlorine and ammonia. Using chloramines in place of chlorine reduces the likelihood of disinfection byproducts formation and their associated health risks.