Our Water Sources & Infrastructure

Our water comes from two primary sources, based on the time of year:

May-September - Well/Groundwater: We use our water wells, drawing from the Arapahoe, Denver, and Lower Dawson Aquifers. These sources are the result of water rights that date back to the formation of the District. This water is treated at our own water treatment facility, stored in the District's two storage tanks, and supplied to customers on demand. Each fall, our operations team shuts down our Water Treatment Plant and activates our interconnect with Highlands Ranch Water.  

October-April - Renewable/Surface Water: We take full advantage of our renewable water resources through an agreement with Highlands Ranch Water. In 2010, the District purchased Hock Hocking (Park County, Colorado) and Upper Platte River rights to increase the community’s water assets to include surface water. This water is stored in Chatfield Reservoir, where CPNMD owns and has access to 1,006 acre-feet of storage capacity. During these months, our neighbor to the north, Highlands Ranch Water, treats our renewable water, which we then pump through our existing interconnect pump station and pipeline into our water distribution system. This facility primarily serves CPNMD, the Town of Castle Rock and Castle Pines Metropolitan District (The Village at Castle Pines). Treated wastewater return flows are captured and used as the primary source of irrigation water for The Ridge Golf Course.

Treating Our Water

In May through September, district water is treated by our own treatment plant. From October to April, Highlands Ranch Water treats our renewable water, which we then pump through our existing interconnect pump station and pipeline into our water distribution system.

This annual switch in water sources not only helps prolong our non-renewable water, but it also allows CPNMD to complete capital projects and do maintenance at our treatment plant that wouldn't otherwise be possible.

Late this 2025 and early 2026, we will be adding new filters to our CPNMD treatment plant. This is the last of many improvements needed for the plant to treat an additional 2 million gallons of water per day (7 million gallons total) to better meet current demand. Read more about the treatment plant upgrades here.

There are slight aesthetic differences in the water from each source that some residents may notice:

• Hardness: Our renewable water (Oct-April) is much harder than that of our deep well aquifers. Residents may notice things like water spots on dishes or fixtures.
   
• Taste: Some residents report that they notice a shift in the taste of our renewable water (Oct-April). It is often described as "earthy, or metallic". This also has to do with the source water differences. The water is absolutely safe to drink and for all other uses. Highlands Ranch Water has been doing work at its treatment plant to help combat this aesthetic issue, and we anticipate that this will be less noticeable in comparison to years past. 

For more information on these sources, visit our latest Water Quality Report to learn more about differences in water taste, hardness, and odor.