Volatile Organic Chemicals (VOCs)

Volatile Organic Chemicals (VOCs) are carbon-containing compounds that evaporate easily from water into air at normal air temperatures. (This is why the distinctive odor of gasoline and many solvents can easily be detected.) VOCs are contained in a wide variety of commercial, industrial and residential products including fuel oils, gasoline, solvents, cleaners and degreasers, paints, inks, dyes, refrigerants and pesticides.

People are most commonly exposed to VOCs through the air, in food, through skin contact, and potentially in drinking water supplies.

Most VOCs found in the environment result from human activity. When VOCs are spilled or improperly disposed of, a portion will evaporate, but some will soak into the ground. In soil. VOCs may be carried deeper by rain, water or snow melt and eventually reach the groundwater table. When VOCs migrate underground to nearby wells, they can eventually end up in drinking water supplies.

Several factors increase the likelihood that a water supply will be contaminated.

  1. The distance between the well and a source of contamination. Many wells contaminated with VOCs are located near industrial or commercial areas, gas stations, landfills or railroad tracks.
  2. The amount of VOCs dumped or spilled. Some spills are small and localized. Others occur over a long period of time, or involve large quantities of contaminants. When a large quantity of chemicals has leaked or spilled, as may occur with leaking underground tanks or industrial spills, a large geographical area may be affected.
  3. The depth of a well can be a factor. Shallow wells are often affected sooner and more severely than deep wells when contaminants have been spilled on surface soils.
  4. The local geology. Groundwater covered by thin, porous soil or sand layers is most vulnerable. Dense, thickly layered soils may slow down the movement of contaminants and may help to absorb them.
  5. Another factor affecting contamination of water is time. Groundwater typically moves very slowly. A spill may take years to reach nearby wells, so wells may not be contaminated until months or years after the spill is discovered.

Testing of private well water for VOCs and petroleum products is indicated if the water has the taste or odor of gasoline or solvents. Wells should also be tested if they are within one to two city blocks (500 to 1000 feet) of a former or existing gasoline service station, or other fuel tanks.

Links for more Information on VOCs

VOCs In Drinking Water

Testing Information-WI State Lab of Hygiene: 1-800-442-4618