Home / Environmental Health / Water and Wastewater / Arsenic in Drinking Water Wells

Arsenic in Private Drinking Water Wells

PRIVATE WELLS CURRENTLY ARE NOT REGULATED BY THE U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA).

Private well owners are responsible for the quality of their drinking water. Homeowners with private wells are generally not required to test their drinking water. However, they can use the public drinking water standards as guidelines to ensure drinking water quality.

Until now, the Maximum Contaminant Level (MCL) for arsenic in drinking water in the U.S. has been set at 0.050 milligrams per liter (equivalent to 50 parts per billion). Recently, the MCL was lowered to 0.010 milligrams per liter or 10 parts per billion as established by the EPA. This revised standard went into effect in 2006 for public drinking water supplies.

Summary

Arsenic occurs naturally in the soil and bedrock throughout many parts of the United States, including Idaho.

Arsenic also occurs in the environment as a result of industrial land use activities and arsenic’s use as both a wood preservative and a pesticide.
Arsenic is a health concern in drinking water and a known human carcinogen.
A water test is the only way to determine the presence and amount of arsenic in well water.

If arsenic is present in well water, several types of home treatment systems are available for removing or reducing the amount of arsenic in water, which includes: reverse osmosis, ion exchange, distillation, and activated alumina.

Potential Health Effects

Arsenic is a toxic heavy metal and is also classified by EPA as a human carcinogen (cancer causing agent). Signs of arsenic poisoning include thickening and discoloration of the skin, stomach pain, nausea, vomiting, diarrhea, numbness in the hands and feet, partial paralysis, and blindness. Most exposure to arsenic occurs through eating or drinking arseniccontaminated food or water.

Chronic arsenic ingestion from elevated levels in drinking water may cause skin cancer and an increase risk for cancers of the bladder, lung, kidney, liver, colon, and prostate. It may also be associated with cardiovascular, pulmonary and other diseases and disorders. Various high-risk groups such as people suffering from malnutrition, protein deficiency, and hepatitis B infection may be more sensitive to the effects of arsenic. Other factors such as genetics, age, metabolism, diet, and health status may also affect health risks due to arsenic exposure.

Indications of Arsenic

It is difficult to predict the presence of arsenic in well water. Arsenic is odorless, tasteless, and colorless. The only way to determine its presence is through a water test.

Sources of Arsenic in Drinking Water

Arsenic is common in areas where there are metallic ore mining operations. Arsenic has also been used as a pesticide, a wood preservative, and in paints, dyes, metals, drugs, soaps, and semi-conductors. Generally, naturally occurring arsenic has not been identified as a major concern in Idaho’s groundwater.

Arsenic has been widely used throughout the United States as a pesticide on fruit orchards and on some other crops. Though use of arsenic as a pesticide has been widely discontinued, it is possible that a buildup of arsenic in the soil has occurred over the years. There are other industrial sites that historically or presently could result in release of arsenic to the environment including: manufacturing of metals and alloys, pharmaceuticals, pesticides, and chemicals, and petroleum refining and waste incineration.

Testing for Arsenic in Private Drinking Water Wells

To determine if arsenic is present, arrange to test your drinking water at a state certified laboratory. Carefully follow laboratory instructions to avoid contamination and to obtain a representative sample. If testing indicates that arsenic is present and treatment is required, other water quality characteristics can effect arsenic treatment and should be tested for, including pH, hardness, iron, manganese, nitrate, nitrite, and sulfate. If any of these are present, pre-treatment may be required.

Generally, naturally occurring arsenic is not a problem in Rhode Island soils and bedrock. If you suspect your property may have been located in or adjacent to an existing or former fruit orchard, it is recommended that private well water be tested for arsenic. This may also apply for those living near existing or former industrial manufacturing operations that have used or currently use arsenic in their processes. Depending on the levels found, water treatment for arsenic removal is generally feasible. Soil testing for arsenic levels is also recommended in these areas.

Corrective Action

Several types of treatment systems are available, including reverse osmosis, ion exchange, distillation, and activated alumina. Before choosing a treatment system, it is important to compare the amount of arsenic present in your water supply with the levels each system can effectively treat.

If arsenic concentrations in well water are elevated, arsenic absorption through skin contact (bathing, dishwashing, etc.) may be a concern and whole house treatment (point-of-entry) may be recommended. If your water tests positive for arsenic, consult with RI Department of Health, (HEALTH), Office of Drinking Water Quality and your physician.

For more information on these treatment options, please contact CDHD Environmental Health - Water/Wastewater - Contacts by County.

Information taken from the Rhode Island Department of Health website.

Additional Resources

Idaho State Lab

Water Sample Testing

Contact

Main Contacts