Government groundwater sampling in Coconino County focusing on aquifer 310COCN shows arsenic was detected in nearly all tested wells, with concentrations ranging from 0.1 to 4.6 micrograms per liter, but no sample exceeded federal arsenic limits.
What additional questions do commercial or industrial water users have beyond residential concerns?
Commercial and industrial operations often require understanding the volume of water used daily, the impact of arsenic on equipment longevity, and compliance with regulations specific to their activities. They may also need to know about waste disposal from treatment processes and potential fluctuations in arsenic levels affecting large-scale water use. Residential water considerations typically focus on health, appliance safety, and taste.
How do arsenic concerns change for large households, second homes, or seasonal properties?
Larger households or properties with intermittent occupancy may face different water use patterns, affecting water treatment system sizing and maintenance needs. For seasonal homes, water may sit in plumbing longer, potentially changing water characteristics, but arsenic levels themselves are primarily influenced by groundwater quality rather than usage. Treatment systems purchased for these properties should be selected with usage variability in mind.
What information should you record before seeking advice on water treatment?
- Sample date and source depth if available
- Any recent water quality tests for arsenic and other elements
- Details about previous water treatment equipment and the nature of its failure
- Household water usage patterns and special considerations such as allergies or sensitivities
How does arsenic concentration vary seasonally or over multiple years in Coconino County’s 310COCN aquifer?
The government record includes 20 samples from 3 wells taken between July 2017 and April 2026. Arsenic was consistently detected, mostly below 1 microgram per liter, with occasional measurements approaching 4.6 micrograms per liter. This indicates some variation over time but no exceedance of federal arsenic limits, showing relatively stable arsenic presence in the aquifer.
How does arsenic enter groundwater or distribution systems in this region?
Arsenic in groundwater of Coconino County’s aquifer can originate naturally from mineral deposits in the earth’s crust dissolving into the water over time. Human activities such as mining or land disturbance might contribute locally, but natural geologic sources are the primary cause. The aquifer's depth from 600 to 1150 feet means arsenic presence results from deep geological conditions rather than surface contamination.
What does a certified lab test report for arsenic show, and how should you interpret it?
A certified laboratory test quantifies arsenic concentration in micrograms per liter (ug/L) for your specific well or supply. Interpretation requires comparing results to federal arsenic limits, which are set to ensure drinking water safety. Because arsenic can vary even between nearby wells, individual testing is essential to understanding your home's water quality precisely.
In summary, government data for Coconino County’s aquifer 310COCN provides a regional arsenic range but cannot define your household’s water without direct testing. If your current water treatment equipment has failed to manage arsenic, considering a direct-purchase Fleck Arsenic Filter system may provide effective treatment tailored to your home's needs.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2026-04-30. These figures describe groundwater sampled in this area. They are not a test of any individual private well - only a test of that well can establish its own water.
On record: U.S. Geological Survey sampling of Arsenic in the 310COCN aquifer (Coconino County): 20 results from 3 wells, median 0.62 ug/L, range 0.1-4.6 ug/L; none above any federal threshold