Drinking Water

Flagstaff's drinking water comes from many different sources: Upper Lake Mary, springs in the Inner Basin of the San Francisco Peaks, and groundwater, which is pumped from the Lake Mary and Woody Mountain well fields, the Inner Basin wells, and local "in-city" wells. Plans are underway to install up to five additional "in-city" wells over the next 10 years. 

The City maintains 23 wells (excluding the shallow Inner Basin wells). We operate and maintain not only production and storage facilities, but also a certified lab to ensure consistently high water quality.

Learn more about our drinking water by watching the 18-minute "Pipelines of the Past" video below.


The treatment process for our water varies depending on the source. Groundwater from wells is disinfected with chlorine while surface water is treated at one of the City's two water treatment plants.

  • Lake Mary Water Treatment Plant: Located on Lake Mary Road, this plant can treat up to 8 million gallons of water per day (8MGD) from Upper Lake Mary. This conventional water treatment plant uses the following processes:
    • Disinfection
    • Filtration
    • Flocculation
    • Sedimentation
    • Coagulation
  • Reservoir Filtration Plant: Our Inner Basin water is high in quality and requires little treatment just filtration, disinfection (with chlorine), and ultraviolet radiation to kill any harmful, disease-causing bacteria that may be present.