What Is Arsenic and Should You Be Concerned?
Arsenic is a naturally occurring element found in bedrock and soil throughout North Carolina's Coastal Plain. When it dissolves into groundwater, it can contaminate private wells, especially in Wilmington, North carolina and surrounding areas. Long-term exposure to arsenic in drinking water has been linked to serious health concerns, including increased cancer risk, cardiovascular issues, and developmental problems in children. The EPA maximum contaminant level for arsenic is 10 parts per billion (ppb), but many health experts recommend lower exposure when possible. If you rely on well water, arsenic is one contaminant you cannot see, taste, or smell, which is why testing is essential.
I'm Eli, a Certified Water Specialist with over 20 years of hands-on experience testing and treating residential water systems. I take arsenic questions seriously because the people asking are usually concerned about someone they love, and that shapes how I explain risk: straight, not scary.
Where Arsenic Comes From in Well Water
Arsenic enters well water when groundwater flows through arsenic-bearing rock formations, especially in coastal and sedimentary geology. In the Wilmington area, the underlying geology includes sediments that can naturally release arsenic into aquifers. Deeper wells sometimes have higher arsenic levels, though shallow wells are not immune. Agricultural runoff, old treated lumber, and industrial activity can also contribute trace amounts, but most arsenic in private wells is geologic in origin. Testing is the only way to know if your well is affected, because arsenic levels vary widely even between neighboring properties.
How to Test for Arsenic Properly
Do not rely on home test strips for arsenic. They are not accurate enough for a contaminant this serious. Instead, use a certified laboratory that follows EPA Method 200.8 or similar protocols for arsenic analysis. Many state health departments offer low-cost or free well water testing that includes arsenic. If you are buying a home with well water in Wilmington, North carolina, request arsenic testing as part of your inspection. Retesting every 3 to 5 years is recommended, or sooner if you notice changes in water quality or if nearby wells test positive. I regularly see homeowners assume their water is fine because it looks clear, but arsenic does not announce itself visually.
What Treatment Methods Actually Remove Arsenic
Reverse osmosis is the most reliable point-of-use treatment for arsenic removal. A quality under-sink HydroClear™ Reverse Osmosis system can reduce arsenic by 95% or more when properly maintained. For whole-house treatment, anion exchange resins and adsorptive media such as activated alumina or iron-based media can reduce arsenic, but performance depends on water chemistry, pH, and competing ions like sulfate. Some homeowners pair a WellFusion™ iron removal system with reverse osmosis for layered protection when both iron and arsenic are present. Water softeners do not remove arsenic. Carbon filters do not remove arsenic. UV systems do not remove arsenic. If a salesperson tells you otherwise, walk away.
Arsenic exists in two forms: arsenite (As III) and arsenate (As V). Most treatment media work best on arsenate, so some systems include an oxidation step to convert arsenite to arsenate before filtration. This is why water chemistry matters. A lab report showing total arsenic is helpful, but speciation testing tells you which form you are dealing with, and that can change which treatment approach works best. I have seen systems undersized or mis-specified because the installer did not account for pH or competing anions, and the arsenic levels barely budged.
Common Mistakes When Treating Arsenic
The biggest mistake I see is treating arsenic without testing first. Some homeowners assume a whole-house carbon filter will handle everything, but carbon does not remove dissolved arsenic. Another common error is installing a reverse osmosis system and never changing the membrane or filters on schedule. RO works, but only when maintained. I also see people install point-of-use treatment at the kitchen sink and assume the rest of the house is safe. If arsenic is in your well, it is in your shower, laundry, and outdoor hose too. For drinking and cooking, point-of-use RO is effective and affordable. For whole-house protection, you need a different approach, and it is rarely a one-size-fits-all solution. Work with someone who understands your water chemistry, not just your zip code.
For broader category context, I would also review Commercial Reverse Osmosis Systems for Industrial Use and Reverse Osmosis Water Filtration Systems for Homes. For supporting education before choosing a system, I would use Reverse Osmosis Water Systems for Homes and Find Your Sulfur Removal System.
Frequently Asked Questions
Can a water softener remove arsenic from well water?
No. Water softeners use ion exchange resin designed to remove hardness minerals like calcium and magnesium. They do not reduce arsenic. You need reverse osmosis or specialized adsorptive media for arsenic removal.
How often should I test my well water for arsenic in Wilmington, North carolina?
Test your well water for arsenic at least once when you move in, then retest every 3 to 5 years. If nearby wells show elevated arsenic or if your water chemistry changes, test sooner.
Does boiling water remove arsenic?
No. Boiling water does not remove arsenic and can actually concentrate it as water evaporates. Use reverse osmosis or certified arsenic removal media instead.
What is the EPA limit for arsenic in drinking water?
The EPA maximum contaminant level for arsenic is 10 parts per billion. Some health organizations recommend even lower exposure, especially for children and pregnant women.
Will a whole-house carbon filter remove arsenic?
No. Standard activated carbon filters do not remove dissolved arsenic. You need reverse osmosis, anion exchange, or adsorptive media designed specifically for arsenic reduction.