What You Need to Know About Organic Chemicals in Drinking Water

Organic chemicals are a group of human-made chemical compounds that have been made for a variety of products—such as pesticides, gasoline, dry-cleaning solvents and degreasing agents. This group of chemicals includes volatile organic chemicals (VOCs), which are substances that contain carbon and evaporate or “off-gas” at room temperature, and synthetic organic chemicals (SOCs).

VOCs and SOCs do not occur naturally in drinking water. When products made with VOCs and SOCs are improperly stored or disposed of, or when a spill occurs, they can contaminate groundwater and drinking water supplies.

Health concerns: Are organic chemicals harmful to my health?

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.

Source: How do organic chemicals get into my water?

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.

Testing: How do I know if organic chemicals are in my water?

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

Test results: Is my result a problem?

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.

Treatment options: Can I remove or lower the levels of organic chemicals in my water?

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

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.

Financial assistance: Is there funding available to help me pay for my water system or treatment?

Vermont Wastewater and Potable Water Revolving Loan Fund

This program, also known as the On-Site Loan Program, is available to certain Vermont residents for the repair or replacement of failed water supply and on-site wastewater systems. The On-Site Loan Program is funded and administered by the Agency of Natural Resources, Department of Environmental Conservation with loan underwriting and servicing provided by the Opportunities Credit Union in Winooski. Your drinking water supply has to be a failed system and you must be living in the residence on a year-round basis to be eligible. The family income cannot exceed 200% of the state median household income. For more information about eligibility and how to apply, call the On-Site Loan Program at 802-461-6051.

The NeighborWorks Alliance of Vermont

The NeighborWorks Alliance is made up of five local organizations offering full affordable housing services for income-eligible individuals. You may qualify for help from this program if you need money to install a water treatment system, drill a well, or repair or replace your septic system. For more information on eligibility, contact the local NeighborWorks Group in your region.

Single Family Housing Repair Loans and Grants

This program offers loans and grants to existing homeowners for well construction, repair and sealing. It's administered by the Rural Development office of the U.S. Department of Agriculture. The program is for low-income families who live in a rural area or a community with a population of 25,000 or less. The family income cannot exceed 50% of the median county income. Individuals who are 62 years of age or older may qualify for a grant or a combination of a loan and a grant. Younger applicants are eligible only for loans.

Burlington, South Burlington, Essex Junction, Winooski and parts of Colchester are ineligible for the program. Even if your property is in an eligible area, your eligibility is still subject to income limits. For more information or to find out if your property is in an eligible area, call the USDA Rural Development Office at 802-828-6022.

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