Organic Chemicals in Drinking Water including Pesticides and Petrochemicals

Most health effects happen when people drink water contaminated with organic chemicals over a long period of time.

Drinking water that contains VOCs can increase your risk for a variety of health problems. Some VOCs have been proven to cause cancer after prolonged exposure, while others are considered possible cancer risks. Consuming drinking water with high levels of PCE or TCE over many years may increase the risk for liver problems and cancer.

People who drink water that contains high levels of atrazine over many years may be at greater risk for cardiovascular problems and reproductive difficulties.

Some people who drink water containing DEHP over many years may be at greater risk for liver problems, reproductive difficulties and cancer.

Examples of VOCs

• Tetrachloroethylene (PCE) is a solvent used in the textile industry and as a component of aerosol dry-cleaning products. It can enter water systems through discharges from factories and dry cleaning facilities.
• Trichloroethylene (TCE) is a solvent that is primarily used to remove grease from fabricated metal parts and is also used in the production of some textiles.

Examples of SOCs

• Atrazine is an herbicide that is widely used as a weed killer, applied on agricultural fields with the greatest use on corn. Although its uses were greatly restricted in 1993, it can still be in the environment.
• Di (2- ethylhexyl) phthalate (DEHP) is the most commonly used of a group of related chemicals called phthalates or phthalic acid esters. The greatest use of DEHP is as a plasticizer (softener) for polyvinylchloride (PVC) and other polymers including rubber, cellulose and styrene. Several packaging materials and tubings used in the production of foods and beverages are PVC-contaminated with phthalic acid esters, primarily DEHP.

These chemicals get into drinking water from human activities. Examples include:

• Pesticides sprayed too close to a well or other water supply
• Accidental chemical spill
• Improper disposal of chemicals down storm drains, household drains, or down the toilet
• From old manufacturing sites where chemicals were improperly disposed of

There are certain factors that could make your water contaminated with organic chemicals:

• Distance between the well and a source of contamination – many wells contaminated with organic chemicals are located near industrial or commercial areas, gas stations, landfills, railroad tracks or farm fields.
• Depth of your well – shallow wells are more likely to be affected than deep wells when contaminants have been spilled or applied on surface soils.
• Local geology – groundwater covered by thin, porous soil or sand layers is most vulnerable, while dense, thickly layered soils may slow down the movement of contaminants and may help to absorb them.

If you suspect that your private drinking water is contaminated by organic chemicals, stop drinking the water and call the Health Department at 802-863-7220 or 800-439-8550 (toll free in Vermont).

Although many organic chemicals found in drinking water are due to contamination, others may be formed when drinking water is treated with chlorine to disinfect it. The chlorine reacts with organic materials found in water and forms certain VOCs known as disinfection byproducts. Learn more about disinfection byproducts

The Vermont Department of Environmental Conservation regulates VOCs in public water systems.

You should test your private well water for VOCs and petroleum products if the water has the taste or smell of gasoline or solvents or an oily sheen to the water. You should also consider testing your water if the well is within 500 to 1,000 feet of a former or existing gasoline service station or other fuel tanks.

Learn more about testing for VOCs, SOCs, and disinfection byproducts

Primary maximum contaminant levels (MCLs) are legally enforceable standards determined by the Environmental Protection Agency to regulate public water systems. Each value represents the highest level of a chemical that is allowed in a public drinking water supply. Vermont action levels (VALs) are numeric guidelines researched and derived by the Health Department for a small number of chemicals that have MCLs but are of specific public health concern. 

Drinking water standards for VOCs

• The MCL for PCE is 5 ppb (parts per billion), and the VAL is 1 ppb.
• The MCL for TCE is 5 ppb, and the VAL is 0.5 ppb 

Drinking water standards for SOCs

• The MCL for atrazine is 3 ppb.
• The MCL for DEHP in drinking water is 6 ppb.

Levels of organic chemicals can be lowered or removed from drinking water with one of the treatment systems listed below.

• Carbon filtration
• Reverse osmosis 

Note that chlorine can damage some reverse osmosis membranes, so pre-treatment may be needed. Reducing the amount of chlorine added to your water, or using an activated carbon filter, can sometimes reduce organic compounds formed during chlorination. If the organic chemicals are not caused by chlorination, it is important to find the source. Additional testing may be needed to determine the level of contamination.

Re-test your drinking water for organic chemicals after any treatment system is installed to make sure levels are below the VAL or MCL.

Funding is available to help you pay for water treatment or to fix your water system. Learn more about financial assistance programs and eligibility.