Arsenic in Arizona Drinking Water: What You Need to Know

Arizona ranks among the top states for naturally occurring arsenic in groundwater. If you're on a private well — or on city water in a rural area — arsenic is worth testing for and taking seriously.

Where Does Arizona's Arsenic Come From?

Unlike most contaminants that come from industrial pollution, Arizona's arsenic problem is mostly natural. The state's geology — volcanic rock, ancient seabeds, and mineral-rich soil — releases arsenic into groundwater as water moves through the ground.

Key facts:

• Arizona's maximum contaminant level (MCL) for arsenic is 10 µg/L, matching the federal EPA standard
• Arsenic above 10 µg/L has been documented in parts of Maricopa, Pinal, La Paz, and Yuma counties
• Well water users are at higher risk than city water customers, but smaller municipal systems sometimes struggle with compliance

Health Risks of Long-Term Arsenic Exposure

Arsenic is a Group 1 human carcinogen. Effects depend on concentration and duration of exposure.

Long-term (chronic) exposure is the real concern for drinking water:

• Increased risk of bladder, kidney, lung, and skin cancers
• Skin changes — darkening, rough patches
• Cardiovascular disease
• Type 2 diabetes risk
• Neurological effects, especially in children

There is no truly "safe" level. The 10 µg/L MCL reflects what's technically achievable at scale, not zero risk.

How to Test for Arsenic

If you're on a private well, you're responsible for testing — the EPA does not regulate private wells.

Options:

• State-certified lab (recommended) — $20–50; results in 5–10 business days
• Home test kits — good for screening; not definitive
• County health department — some Arizona counties offer low-cost or free well testing

City water customers: your utility publishes an annual Consumer Confidence Report (CCR). Look for arsenic in the detected contaminants table.

Best Filters for Arsenic Removal

Standard carbon filters do not remove arsenic. You need a system specifically rated for it.

Filter Type	Arsenic Removal	Notes
Reverse Osmosis (RO)	90–96%	Best for drinking water; most cost-effective under-sink option
Activated Alumina	90–99%	Often used in whole-house systems; media needs periodic replacement
Iron Oxide / KDF Media	90–95%	Effective; often combined with other media
Distillation	99%+	Removes nearly everything; slow and energy-intensive
Standard Carbon Filter	<10%	Does not remove arsenic

For most Arizona homeowners, an under-sink reverse osmosis system is the practical solution for drinking and cooking water. For whole-house treatment on a high-arsenic well, an activated alumina whole-house filtration system is the better choice.

RO vs. Whole-House: Which Do You Need?

Under-sink RO makes sense when:

• City water tests below 50 µg/L
• You want protection at the tap for drinking and cooking
• Budget is a priority

Whole-house filtration makes sense when:

• You're on a private well with elevated arsenic
• You want protection at every tap — shower, laundry, cooking
• Arsenic levels are above 25 µg/L

What to Do If Your Well Tests High

1. Stop drinking the water immediately until a filter is in place
2. Retest — confirm with a second sample from a certified lab
3. Install a filter sized for your flow rate and arsenic level
4. Test again after installation to confirm removal efficiency
5. Retest annually — arsenic levels shift with drought and groundwater changes

If your municipal system is out of compliance, contact the Arizona Department of Environmental Quality (ADEQ) — they maintain a searchable database of community water system compliance records.

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For well owners and rural Arizona residents, this isn't a hypothetical risk. If you haven't tested your water in the past two years, now is the time. If your results come back elevated, we can help you match the right system — whether that's a point-of-use RO for the kitchen tap or a whole-house setup for a high-arsenic well. Reach out with your water test results and we'll point you in the right direction.