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Tests for Arsenic in Drinking Water InspectAPedia®  -     Sources of Arsenic in water Health effects of arsenic exposure Standards and limits for arsenic exposure How to remove arsenic from water How to test water for arsenic contamination

This article discusses the detection of arsenic in drinking water, sources of arsenic in water, arsenic exposure limits, and how to remove arsenic from drinking water. Sources of arsenic in drinking water may be from natural occurrence of arsenic in soils and rock, or in some areas from industrial waste.

Because arsenic contaminants in drinking water cannot be tasted by the consumer, if your drinking water is coming from a private well and if there is particular risk of arsenic in your drinking water the water source should be tested. [Above we show a photograph of the arsenic test lamp used for detection of arsenic in drinking water - courtesy of Aquacheck Water Testing Laboratory].

If your drinking water is coming from a municipal supply, or from a privately-owned water company that has more than 15 service connections or serves 25 people more than 6 months of a year, the water company or municipality are required to regularly test for arsenic in your water and you should not need to order this test privately.

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US EPA Data on Arsenic in Drinking Water

The following data is derived from the US EPA:

The U.S. EPA has set the arsenic standard for drinking water at .010 parts per million (10 parts per billion) to protect consumers served by public water systems from the effects of long-term, chronic exposure to arsenic.  That maximum contaminant level (MCL) for arsenic in drinking water for total arsenic level, regardless of whether the arsenic is in inorganic form. Public water systems have been required to comply with this standard since January 23, 2006.

"Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices.

Human exposure to arsenic can cause both short and long term health effects.  Short or acute effects can occur within hours or days of exposure. Long or chronic effects occur over many years. Non-cancer effects can include thickening and discoloration of the skin, stomach pain, nausea, vomiting; diarrhea; numbness in hands and feet; partial paralysis; and blindness. Arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate."

Sources of Arsenic in Drinking Water

Arsenic occurs naturally in rocks and soil, water, air, and plants and animals. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks and forest fires, or through human actions.

Approximately 90 percent of industrial arsenic in the U.S. is currently used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps and semi-conductors. High arsenic levels can also come from certain fertilizers and animal feeding operations. Industry practices such as copper smelting, mining and coal burning also contribute to arsenic in our environment.

Higher levels of arsenic tend to be found more in ground water sources than in surface water sources (i.e., lakes and rivers) of drinking water. The demand on ground water from municipal systems and private drinking water wells may cause water levels to drop and release arsenic from rock formations.

Compared to the rest of the United States, western states have more systems with arsenic levels greater than EPA’s standard of 10 parts per billion (ppb). Parts of the Midwest and New England have some systems whose current arsenic levels are greater than 10 ppb, but more systems with arsenic levels that range from 2-10 ppb. While many systems may not have detected arsenic in their drinking water above 10 ppb, there may be geographic "hot spots" with systems that may have higher levels of arsenic than the predicted occurrence for that area.

What To Do About Arsenic in Drinking Water

Scott Bradley, Aquacheck Water Testing Laboratory

Arsenic is a soft, semi-metallic element that is found naturally in our environment. We also see arsenic introduced through orchards, treated lumber, and certain industrial processes such as glassware and electronic components production.

Arsenic exposure limits - maximum levels allowed in drinking water

The MCL, or maximum contaminant level had been set at 50 ppb (parts per billion) from 1975 until January, 22, 2001 when the new EPA (Environmental Protection Agency) level became 10 ppb. Why lower the level five-fold? What did the EPA discover after studying arsenic to make them drop the level that much?

Effects of exposure to Arsenic

Long term exposure to arsenic in drinking water has been linked to cancer of the bladder, lungs, skin, kidneys, liver, and prostate. Other non-carcinogenic effects may include cardiovascular, pulmonary, immunological, neurological, and endocrine (diabetes) disorders. Large doses of arsenic can be lethal and has been the "poison-dujour" for centuries!

Arsenic exposure standards can be improved

Adopting the new, stricter standards will provide increased protection for over 54,000 community water systems - such are the type that serve small cities and towns, apartments, and mobile home parks. Also, over 20,000 systems that serve such institutions as schools, churches, and nursing homes also must have complied to the new regulations by January 23, 2006.

Geographic "hot spots" where Arsenic is Found in Drinking Water

In the laboratory, we analyze arsenic from all parts of the United States. Arsenic is more common in the U.S. in drinking water from wells in the Southwest and Western states. We find geographical "hot-spots" where arsenic turns up at higher levels. "Hot spots" of arsenic contamination might also be found in other states, particularly if it is coming from industrial contamination. It is not uncommon to find levels well over 100 ppb in some areas.

Arsenic is odorless and tasteless, so the only way for you to tell if your well or source water has arsenic in it is to have it analyzed by a laboratory certified for that parameter. To find a certified lab., you can check with your state health department or call the Safe Drinking Water Hotline at, 1-800-426-4791.

How to remove arsenic from drinking water

Arsenic can be removed from water, but we need to take a closer look at the element itself.

Arsenic can come in two forms, or valences. One, is inorganic, the other organic. The EPA MCL of 10 ppb is based on total combined arsenic. One form, trivalent or AsIII is also known as arsenite.

The other form, pentavalent, or AsV is also known as arsenate. Most manufacturers produce filters that will remove pentavalent arsenic as long as the starting level is less than 300 ppb. Speciation can be performed to determine which forms you have and in what proportions, but as you read further, it is not really necessary to speciate.

Typically, the trivalent form is converted to pentavalent form using free chlorine or other similar oxidation chemical because AsV is easier to remove. As previously mentioned, have a certified lab give you the total arsenic number, then let a qualified and experienced treatment professional take care of the filtration.

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• Scott Bradley, author. Scott Bradley is Laboratory Director for Aquacheck Laboratory, Inc. PO Box 87 05151 1-800-263-9596. A more brief version of this article appeared in Aquacheck Laboratory's Water Wisdom Tips and Newsletter, Issue # 6, 2007. www.Aquacheck-VT.com offers other water supply tips in its Water Wisdom section. The laboratory also provides water test kits and offers a free newsletter. The website author, D. Friedman has edited and added to the original material provided by Mr. Bradley.
• US EPA resources on arsenic in drinking water: see epa.gov/safewater/arsenic/index.html and the US EPA's private drinking water well safety website at epa.gov/safewater/privatewells/index2.html

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