Extension and Ag Research News


Well Owners Need to Check for Arsenic

Private well owners should have their water tested for arsenic.

How confident are you that your drinking water is not contaminated with arsenic?

Households served by rural or municipal water systems have numerous people ensuring their drinking water safety, but those using private wells cannot make that assumption and must have their drinking water analyzed by a laboratory, North Dakota State University Extension Service water quality associate Roxanne Johnson says.

“By not testing, your unfounded confidence may damage your health,” she warns.

Arsenic, a semimetalic element, is tasteless and odorless. It can enter your ground water from natural deposits in the earth or agricultural and industrial practices. In some areas of North Dakota, increased rates may be attributed to the historical use of arsenic-based grasshopper bait and naturally occurring sources.

An Australian study shows arsenic that’s ingested is absorbed through the small intestine, although minimal amounts can be absorbed through skin contact and inhalation.

Noncancerous effects of ingesting arsenic can include thickening and discoloration of the skin, stomach pain, vomiting, diarrhea, numbness in the hands and feet, partial paralysis and blindness if it’s consumed at levels higher than those seen in North Dakota’s public waters. Arsenic also has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver and prostate in studies of long-term exposure.

According to Larry Thelen, administrator of the drinking water program at the North Dakota Department of Health, a map of North Dakota would show a band of high levels of arsenic running from the northwestern corner of the state through the middle and on to the southeastern corner. Arsenic levels in these areas are higher than standards set in the Environment Protection Agency’s Safe Drinking Water Act.

The original EPA standard for arsenic in drinking water was 50 parts per billion (ppb). The Safe Drinking Water Act, which Congress enacted in 1974, directed the EPA to provide enforceable health goals and increased protection by reducing the standard to 10 ppb due to the effects of long-term, chronic exposure to arsenic.

To comply with the standards and reduce the risk of illness, public drinking water systems must make changes in their treatment of ground water. Twenty-six public water systems in North Dakota were required to reduce their arsenic levels. Thelen reports that five of them still have to finalize their renovations, which are scheduled to be completed in 2008.

The EPA’s guidelines do not apply to private wells, so all private well owners should have their drinking water tested, Johnson says. Well owners must specify they want their water tested for arsenic because this test does not fall under the normal chemical analyses laboratories in North Dakota perform.

Bottles for collecting water samples are available at many county Extension offices or by calling the following certified labs that do arsenic testing. This list includes the prices the labs charge.

  • Fargo Cass Public Health Environmental Laboratory, 401 3rd Ave. N., Fargo, ND 58102; (701) 241-1360; $20
  • Minnesota Valley Testing Laboratories Inc., 1411 12th St. S., Bismarck, ND 58504; (701) 258-9720; $23
  • North Dakota Department of Health, Chemistry Division, 2635 Main Ave. E., P.O. Box 937, Bismarck, ND 58501; (701) 328-6140; $19.36.

Many treatments are available to reduce the level of arsenic in drinking water. Several types of filters can be used, including reverse osmosis (ion exclusion), ultrafiltration (activated alumina) and water softening (ion exchange).

The treatment best suited for each well owner’s situation depends on the level of arsenic and other elements that may influence the treatment’s effectiveness, Johnson says. She urges well owners to consult their county Extension agent or a private water treatment provider to help determine which process will ensure the quality of their drinking water.

“What we do know is disinfecting water by chlorination or by using most mechanical filters is not effective in removing arsenic from water unless natural irons are present and enough time passes for the chlorination to remove the iron with the arsenic,” she says. “Do not heat or boil your water to remove arsenic. Because some of the water will evaporate, boiling water can increase the concentration of arsenic in your water.”

Public water users concerned about the quality of their drinking water may review test results for their water source by requesting the annual water quality report their water supplier provides.

Information on interpreting this report is available at http://www.ag.ndsu.nodak.edu/abeng/news%20releases/watchforwater.htm.

For more information, contact Johnson at (701) 231-8926 or mailto:Roxanne.M.Johnson@ndsu.edu.

NDSU Agriculture Communication

Source:Roxanne Johnson, (701) 231-8926, Roxanne.M.Johnson@ndsu.edu
Editor:Ellen Crawford, (701) 231-5391, ellen.crawford@ndsu.edu
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