Arsenic in Groundwater and Drinking Water

Arsenic in groundwater and drinking water is a concern for homeowners, especially those using private wells in New Jersey, where it ranks among the most common contaminants exceeding safety standards.

What Arsenic in Water Means

Arsenic in groundwater and drinking water is a concern for homeowners, especially those using private wells in New Jersey, where it ranks among the most common contaminants exceeding safety standards.

Arsenic is a naturally occurring element found in soil and rock. As groundwater moves through these materials, small amounts can dissolve into the water supply. There are also minor contributions from past human activity. Older pesticides, industrial materials, and treated wood have left traces in some regions. Still, for most private wells, natural sources remain the main cause.

In many locations, levels stay low and don't raise concern. The issue starts when concentrations move past accepted limits. Some areas have a higher chance of arsenic due to the types of rock below the surface. That's why one well may show elevated levels while another nearby does not. Even short distances can lead to very different readings. This explains why arsenic is often a regional issue rather than a single isolated problem. It's tied closely to the ground beneath each property.

Problems Arsenic Can Cause

Long-term exposure to elevated arsenic levels has been linked to several health concerns. These may include changes to the skin, such as darkening or spots. Arsenic also been connected to effects on the cardiovascular and circulatory systems and, in some cases, impacts on nerve function. Over time, higher exposure levels have also been associated with increased risk of certain cancers, particularly involving the skin, bladder, and lungs.

These outcomes are tied to consistent exposure over many years, not occasional use. That distinction matters because it keeps the focus on long-term water quality rather than short-term contact.

One of the more frustrating aspects of having arsenic in your water is that there's no clear warning sign in daily use. The water doesn't look or taste different, and symptoms don't appear right away. That delay can make it harder to connect the source to the issue without proper testing.

Why Private Wells Are More at Risk for Arsenic in Water

Public water systems follow strict testing schedules and reporting rules. If something exceeds a standard, action is taken and users are informed. Private wells work differently. There's no automatic testing unless the homeowner arranges it, and no ongoing oversight. A private well can go years without being checked, even in areas where arsenic is known to occur.

Another factor is variability. Well depth, construction, and surrounding geology all play a role in water quality. Two homes on the same street can have very different results due to these differences.

Arsenic in New Jersey Wells

In New Jersey, arsenic is the second most common contaminant that exceeds drinking water standards in private wells across the state (with coliform bacteria being the first).

Certain parts of New Jersey have geological conditions that make arsenic more likely to appear in groundwater. Over time, water moving through these formations can carry arsenic into wells.

The state requires testing during real estate transactions for many properties with private wells. That step helps identify issues before a sale is completed. Still, testing at one point in time doesn't cover long-term changes, because water conditions can shift. A well that once tested below the limit may show higher levels later. This is why ongoing testing remains important even after a home is purchased.

How to Test for Arsenic in Your Water

Testing is the only reliable way to confirm if arsenic is present in your water. Certified laboratory testing provides accurate measurements and identifies the form of arsenic in the water. Home test kits can give a general idea, but they lack the precision needed for decisions about treatment.

Testing is recommended when moving into a home with a private well. After that, periodic testing helps track any changes over time. Some homeowners test every few years, while others prefer a shorter interval if there are known concerns nearby. It's also important to test before installing any treatment system. That step helps match the system to the actual conditions instead of guessing.

Once test results are available, the next step is understanding what the numbers mean. This part can feel confusing at first, but it becomes clearer with a simple approach.

The U.S. Environmental Protection Agency has set a maximum contaminant level of 10 parts per billion, or 10 ppb. This standard is used as a guide for safe long-term use. When a test shows a level above 10 ppb, it means the water doesn't meet that guideline. It doesn't mean there's immediate danger. The actual number is what matters. A reading slightly above the limit carries a different weight than a much higher reading. A slightly higher reading may call for a different approach than a much higher one. This helps guide both urgency and system selection.

Looking at results over time also helps. If multiple tests have been done, patterns can show whether levels are stable or changing. That information adds context and helps avoid rushed decisions.

Types of Arsenic and the Differences

Arsenic in water usually appears in two forms, arsenic III and arsenic V. The difference between them becomes important when selecting a treatment method.

Arsenic V is easier to remove using standard filtration systems. Arsenic III is more difficult and may require an added step before removal. This step typically involves converting it into a form that can be filtered more effectively.

Laboratory testing can identify which type is present. Without that detail, it's harder to choose the right system. This is why detailed testing plays a key role before moving forward. Knowing the type helps avoid installing a system that doesn't fully address the issue.

Water Treatment Options That Reduce or Remove Arsenic

There are several proven ways to reduce arsenic in drinking water. The right water treatment choice depends on the level of arsenic, the form present, and how the water is used in the home.

Reverse Osmosis

This is one of the most common, reliable, simple options for homes. It uses a semi-permeable membrane to remove dissolved contaminants. It's typically installed under a sink (point-of-use) for drinking and cooking water, and can remove around 95% or more of arsenic when properly set up.

Reverse osmosis works best when arsenic is in the arsenic V form. If arsenic III is present, pre-treatment may be needed.

Adsorptive Media Filters (Iron-Based Filters)

These are widely used for both residential and larger systems. They use materials like iron oxide or activated alumina. Arsenic sticks to the surface of the media and gets removed. These work best as a whole-house treatment, where arsenic levels are moderate and in situations where water chemistry supports adsorption. This method is widely used because it removes arsenic without changing overall water quality much.

Ion Exchange Systems

These systems work somewhat like water softeners. They swap arsenic ions with other ions (usually chloride). They're best for whole-house systems and water that already works well with ion exchange chemistry. They're effective mainly for arsenic V, less so for arsenic III unless pre-treated.

Oxidation + Filtration Systems

This is usually a two-step process, not a single filter. Step 1 is converting arsenic III into arsenic V using oxidants like chlorine or permanganate. Step 2 is removing it using filtration (often iron-based media). This approach is important because arsenic III is harder to remove directly.

These systems are best for waters that have higher arsenic levels, and systems that already treat iron or manganese.

Coagulation and Filtration

These are more common in municipal systems and for large-scale treatment. They're not typically used in standard residential setups due to complexity. Chemicals are added to bind arsenic into particles, and those particles are then filtered out. This method can achieve strong removal rates, especially in larger systems.

Iron Removal Systems (Special Case)

In some wells, arsenic attaches to iron naturally. When iron is removed, arsenic may be reduced as well. This type of water treatment system is a special case where it's often paired with oxidation systems. It works best with wells that have both iron and arsenic present.

Water treatment systems require ongoing attention. Filters need replacement, and systems should be checked to confirm they're working as intended.

Costs vary based on system type and installation. Smaller systems tend to cost less upfront, while whole-house systems involve a larger investment. Maintenance adds to the long-term cost but keeps the system effective. Skipping maintenance can reduce performance. A system that worked well at first may lose effectiveness if it isn't maintained over time.

Periodic retesting of the water is also recommended. Even after a system is installed, testing confirms that arsenic levels remain below the target level.

Arsenic in groundwater is a known issue in many regions, including New Jersey, where private wells are common. With proper testing, clear understanding, and consistent treatment, homeowners can manage it and keep drinking water within safe levels.