Arsenic in Yavapai County Well Water: What Every Private Well Owner Needs to Know

If you live on a private well anywhere in Yavapai County, the most consequential thing you can do this year is order an arsenic test. Not because arsenic is rare here — because it’s common, geological, and impossible to detect without a lab.

The data: this isn’t a few wells

Two pieces of peer-reviewed research define the scope:

1. Arsenic Concentrations in Ground and Surface Waters across Arizona, published in Science of the Total Environment, sampled hundreds of wells across the state. The study found that more than 40% of samples from Yavapai and Pinal Counties exceeded the EPA’s 10 ppb arsenic limit. Areas with historical mining or deep groundwater exploration showed clusters of dramatically higher concentrations.

2. The Arizona Department of Health Services’ Cornville Health Consultation — a formal study of arsenic in private wells in Cornville, an unincorporated community in eastern Yavapai County — found arsenic levels ranging from 15 to 952 micrograms per liter (µg/L). The high end is 95× the EPA’s legal limit.

Arsenic in Northern Arizona groundwater isn’t industrial pollution. It’s geological — the same volcanic and granitic bedrock that makes the high desert beautiful is leaching naturally-occurring arsenic into the aquifer. There’s no upstream fix and no remediation. The only path is treatment at your home.

Why arsenic at low levels is still serious

The EPA’s Maximum Contaminant Level for arsenic in drinking water is 10 parts per billion (ppb). The World Health Organization recommends the same. The EPA, ATSDR, and WHO all classify inorganic arsenic as a Group 1 human carcinogen. Long-term ingestion above 10 ppb is associated with:

• Bladder, lung, and skin cancers
• Cardiovascular disease (increased risk of heart attack and stroke)
• Type 2 diabetes
• Developmental and cognitive effects in children
• Skin lesions and pigmentation changes

Arsenic is colorless, odorless, and tasteless in drinking water. There is no DIY way to detect it. People drinking 95×-the-limit Cornville water for years had no idea until the lab tests came back.

How to test your well

Two paths:

1. Aqua Cat $179 Premium Water Test. Screens arsenic alongside 30+ other contaminants in one sample. Results in 7–10 business days. We read every report with you and translate the numbers into plain English.

2. State or county-funded testing. The Arizona Department of Environmental Quality (ADEQ) and Yavapai County Health Department periodically run free or subsidized testing programs. These are excellent — just slower.

If your well has never been tested, do it this month. If it’s been more than 12 months since the last test, do it this month. Arsenic levels can change as the water table drops or after well-pump service.

How arsenic is removed

The EPA recognizes three Best Available Technologies for residential arsenic removal:

1. Whole-house arsenic adsorption media — iron-based selective resin captures arsenic V across every tap. $2,500–$4,500 installed. Best when you want every shower and sink arsenic-free.
2. Point-of-use reverse osmosis — rejects 95+% of arsenic V at the kitchen sink. $800–$1,800 installed. Most cost-effective if your concern is drinking water only.
3. Combined whole-house + RO — the gold standard. $3,500–$6,000 installed.

One subtlety many plumbers miss: arsenic exists in two oxidation states, arsenic III (more toxic, harder to remove) and arsenic V. RO membranes and most adsorption media reject arsenic V at 95+%, but pass arsenic III. Yavapai County wells are usually arsenic V, but if your test shows III, the system needs a pre-oxidation stage (typically chlorine or potassium permanganate) to convert it to V before treatment. Aqua Cat tests the speciation and sizes accordingly.

Full system options are on our arsenic removal page.

What to do today

1. If your well has never been tested, order the Aqua Cat $179 Premium Water Test. Today. Don’t wait until you have symptoms — arsenic doesn’t cause acute symptoms.
2. While you wait for results, drink and cook with bottled water or RO-filtered water if you have a hunch your well is high-risk (proximity to mining, deep wells, neighbors with confirmed contamination).
3. When results come back, schedule a free Aqua Cat consult to read them and design the right treatment system.
4. After treatment is installed, test again to confirm arsenic is below detection. Aqua Cat includes that confirmation test on every install over $2,500.

Arsenic is a long-term ingestion risk, not an acute one. Showering and laundry are fine. The clock is on years of exposure, not days — but the clock starts ticking the day you move in. Get tested.