Arsenic in Drinking Water
Arsenic is a natural element found in some rocks and soil in Vermont. Drinking
water wells located in these areas may produce water that contains arsenic.
Arsenic has no taste or smell. Water must be tested to know if it contains
arsenic and at what level. The Deparment of Health Laboratory and private
certified laboratories offer water testing for arsenic. It is recommended that
private well owners test their drinking water to learn its arsenic level.
If your drinking water at home, work or school is provided by a public water
supply, testing for arsenic is required on a set schedule. Contact the water
provider or the Vermont Department of Environmental Conservation’s Water
Supply Division for more information.
Health Concerns
Health effects due to drinking water with arsenic depend both on how much
arsenic is in the water, and for how many years the water has been used for
drinking. Ingestion of arsenic over a long period of time has been linked to an
increased lifetime risk of getting bladder, lung or skin cancer. Research is also
ongoing on arsenic’s links to skin and cardiovascular diseases, diabetes or
other cancers.
Exposure
Drinking water with high levels of arsenic over a long period of time is one
source of exposure. People may be exposed to arsenic in several other ways -
- Fossil fuels - burning of fossil fuels and smelting can release arsenic
into the air where it can be inhaled. - Pressure treated wood can be a source of arsenic during sawing or
sanding. - Pesticides formerly used in orchards had arsenic as an ingredient, and
some soils in those areas may still contain arsenic.
People routinely take in very small amounts of arsenic from the air, water,
and from food. Of these, food is usually the largest contributor. This is
generally due to the levels found in seafood and fish, but this form of arsenic is
different than the arsenic stored in rocks and soil, and is far less harmful.
Drinking Water Standard
The federal standard for arsenic in public drinking water was 50 parts per
billion (ppb) for decades. Recently, the U.S. Environmental Protection Agency
announced a stricter and more health protective standard of 10 ppb. Public
water supplies in Vermont that provide water to communities, schools and
workplaces must meet this new standard.
Owners of private wells with arsenic levels at or above 10 ppb should consider
installing an arsenic removal treatment system, using bottled water, or getting
water from a known safe location.
Treatment
Arsenic levels can be reduced in drinking water with treatment. After the treatment system is installed, a follow-up sample of the treated water should be tested to make sure the arsenic level is below the 10 ppb standard.
Arsenic in water comes in two forms. The systems below remove both types:
- Adsorptive filters - new specialty filters to remove arsenic from water are being developed for both private well owners and public works. As the water flows through the filter, arsenic adsorbs (sticks to) to the filter which contains a type of granular iron oxide.
- Countertop (plug-in) distillation units boil water and then recondense the steam. These units can produce several gallons of arsenic-free water per day.
The treatments listed below all require water to go through an “oxidation” process first, in order to change arsenic to a form that can be removed. Options for the second step are:
- Anion exchange - this type of treatment system exchanges arsenic compounds for chloride using a specialty resin. When the resin is saturated with arsenic, a pump rinses the resin (backwash cycle) and sends the arsenic down the drain.
- Reverse osmosis - this technology uses home water pressure against a thin membrane. Only arsenic-free water can travel through it. The membrane is continually rinsed. Reverse osmosis is generally chosen as a treatment for one household tap, typically the kitchen tap.
- Carbon block - this technology is being used to reduce total arsenic as the water passes through a solid carbon block. Look for National Sanitation Foundation Standard 53 Certification which verifies that the filter’s arsenic reduction claim has been confirmed.
Larger public water systems with trained water system operators have other options for treatment. These include coagulation/filtration, activated alumina, and lime softening. In addition, public water supplies sometimes blend two or more water sources to reduce arsenic levels through dilution.
For More Information
- Vermont Department of Health
- http://healthvermont.gov
- Technical assistance - 1-800-439-8550 (Vermont only) or 1-802-863-7220
- Laboratory services - 1-800-660-9997 (Vermont only) or 1-802-863-7335
- Vermont Department of Environmental Conservation
- www.vermontdrinkingwater.org
- Water Supply Division - 1-800-823-6500 (Vermont only) or 1-802-241-3400
- U.S. Environmental Protection Agency (EPA) -
- National Sanitiation Foundation - www.nsf.org/certified/dwtu
- U.S. Department of Health and Human Services
- Agency for Toxic Substances and Disease Registry -