Updated May 2026 · Wicked Pure Water Co
New Hampshire has one of the most significant naturally occurring arsenic problems of any state in the country. It is not an industrial accident or a pollution event. It is geology. And because arsenic in well water is completely invisible, most homeowners who have it have no idea until they test.
Why New Hampshire has so much arsenic
Arsenic is a natural element locked inside rock. Much of New Hampshire sits on granite and related bedrock formations that contain arsenic, and as groundwater moves through that rock over time, it dissolves small amounts and carries them into the bedrock wells that homes draw from. The problem is most concentrated in the southern and central parts of the state, where the granite belt runs through towns like Bedford, Amherst, Hollis, and the surrounding region. Studies from the United States Geological Survey and the University of New Hampshire have mapped these patterns for years, and the state Department of Environmental Services estimates that a meaningful share of private wells exceed the safety standard.
Why arsenic is a serious health concern
Long-term exposure to arsenic in drinking water is linked to a range of serious health effects, including several types of cancer, cardiovascular disease, and developmental effects in children. The risk comes from years of daily consumption, not a single glass, which is part of what makes it so easy to ignore. Because the exposure is slow and silent, a well can quietly sit above the safe limit for a decade while the family drinking from it feels completely fine.
You cannot detect arsenic without a test
This is the single most important fact about arsenic. It has no taste, no smell, no color, and it does not change how your water looks or feels. There is no home symptom to watch for and no filter pitcher that quietly handles it. A laboratory test is the only way to know your level. Arsenic is measured in parts per billion, and the result is compared against the legal limit.
New Hampshire's stricter arsenic standard
The federal limit for arsenic in drinking water is 10 parts per billion. New Hampshire decided that was not protective enough. The state lowered its own standard to 5 parts per billion, one of the strictest in the nation, which means a well that would pass the federal test can still be above New Hampshire's limit. When we test, we measure against the 5 ppb state standard so you are seeing the number that actually reflects current New Hampshire policy.
How arsenic is removed from well water
The good news is that arsenic is very treatable. For whole-home protection, a point-of-entry treatment system is installed where the water line enters the house, so every tap is covered. Depending on the well's chemistry, that may use adsorption media or anion exchange, and it is often paired with treatment for radon, uranium, iron, and hardness, since those frequently appear together in New Hampshire bedrock wells. For drinking and cooking water specifically, an under-sink reverse osmosis system removes arsenic very effectively at the kitchen tap. The right approach depends entirely on your test results, which is why testing always comes first.
Arsenic is the most common serious contaminant we find in New Hampshire well water, and it is also one of the most fixable. The barrier is almost never the technology. It is simply knowing the number, and a free test tells you where you stand.