Arsenic and Your Well Water: Part 1 of 3

 Arsenic stone


Arsenic is a natural element that is commonly found in water, air, soils and plants and animals. Agricultural and industrial sources can also release arsenic into the environment.

It is can be found in two different forms:

  • Inorganic –  these inorganic compounds form from the interaction with oxygen, chlorine, and sulfur, usually found in building products, industrial effluent, and in fresh water exposed to these point sources. This form is considered the more toxic form, as it has been linked with the development of certain cancers.
  • Organic – This is the much less toxic form. It  is commonly used in pesticides and found in certain organisms, particularly fish and shellfish who accumulate it in their tissues.

pure water, no arsenic

How does it affect you if it’s in the environment?

More specifically, it can reach your body in many ways including:

  • Crop pesticide runoff or leaching into the groundwater that is pumped up through wells
  • Inhalation of pressure-treated lumber that uses arsenic preservatives
  • Effluent or toxic air from glass manufacturing
  • Runoff from copper and lead smelting, arsenic is an additive used often
  • As arsine gas to increase the electrical conjunctions in semiconductors
  • Medicine used in the 1800s through the early 1900s contained low doses of arsenic to treat diseases such as psoriasis and syphilis.
  • Apple juice
  • Groundwater in regions with bedrock geology that is largely pyritic

Many sources of arsenic runoff into the environment in the United States have been regulated, and some practices that involve arsenic release in the process have even been outlawed. Though, arsenic does not break down once in a biotic system. It can only change between its two forms.

What about Arsenic in the water I am drinking?

It is often is a substitute element in the crystal structure of the mineral pyrite. Regions where the groundwater interacts consistently with arsenian pyrite have very high and very unsafe concentrations of the element. Countries such as Bangladesh must constantly deal with arsenic related water health hazards for this reason.

Arsenic - Piece of Arsenic Erythrite

Piece of Arsenic Erythrite

Even if not exposed to arsenian pyrite, city water resource reservoirs can accumulate high concentrations of arsenic as well. To address the issue, the US Environmental Protection Agency (EPA) has placed federal maximum contaminant levels for drinking water at 10 parts per billion (ppb) arsenic.

The Food and Drug Administration (FDA) has placed the same maximum contaminant level of arsenic in bottled water and apple juice. Other food doesn’t yet have federal concentration limits for arsenic.

High levels of exposure can be very dangerous. Get your water tested for this contaminant as soon as possible if you may be in an area affected by those sources listed above.

Check back at the beginning of next week for Part 2: Health Risks of Arsenic in Water, the second of our three part series about this water contaminant.

About the Author Gerry Bulfin

Need help with your well water? I have been assisting homeowners, small communities and businesses improve their well water quality since 1989. Please email me at if you have a question about water testing, test kits or well water systems in general. Gerry Bulfin CWS-IV Master Water Specialist WQA Certified Licensed California Water Treatment Contractor