Centers for Disease Control and Prevention Statement:

Over 15 million U.S. households obtain their drinking water from private wells , which are not covered by the United States Environmental Protection Agency (EPA) regulations that protect public drinking water systems. Although the United States has one of the safest drinking water supplies in the world, sources of drinking water can still become contaminated through naturally occurring chemicals and minerals (for example, arsenic, radon), local land use practices (for example, pesticides, chemicals, animal feeding operations), malfunctioning wastewater treatment systems (for example, sewer overflows), and other sources. Contamination of a private well can impact not only the household served by the well, but also nearby households using the same aquifer.
Owners of private wells are responsible for ensuring that their water is safe from contaminants. Private wells should be checked every year for mechanical problems, cleanliness, and the presence of coliform bacteria, nitrates, and any other contaminants of local concern. A local health department or water well systems professional can help ensure delivery of high-quality water from an existing well or, if needed, help locate and construct a new well in a safer area. Additional information about well maintenance and water testing is available at Healthy Water's Well Testing (http://www.cdc.gov/healthywater/drinking/private/wells/testing.html).

This CDC statement makes reference to a myriad of possible contaminants, but the two chemicals that have recently been of concern in lower Fairfield County are chlordane and dieldrin. These two substances were used for crop and termite control until the 1980s when they were banned in the United States. Residual concentrations may be evident in some private wells due to leaching from affected areas. Therefore, New Canaan Health Department recommends those dwellings with private wells to follow CDC guidelines as to appropriate water testing. Residents can test for concentration levels of these synthetic organic compounds (SOCs) by contacting a state certified water laboratory and discussing the appropriate steps necessary to test chlordane and dieldrin levels in private wells. (Please refer to the link below for Connecticut’s list of state certified laboratories.)

It is important to know that the basic potability test for private wells only tests for the presence of bacteria and a few chemical compounds. Pesticides, volatile organic compounds (VOCs), SOCs and other contaminants such as radon and heavy metals are not included and therefore, The Connecticut Department of Public Health (DPH) recommends that private wells be tested annually for a full spectrum of contaminants.
The State of Connecticut sets health-based action levels for many chemicals in private well water. Action levels are used to decide when water treatment is needed. DPH considers health risks to be insignificant if exposure to chemical concentrations is below a specified action level. It is also important to know that a concentration exceeding an action level does not necessarily mean a health effect will occur. The action level for dieldrin and chlordane is 0.03 micrograms per liter (ug/L) or parts per billion (ppb).

In the event a private well exceeds chlordane and/or dieldrin action levels, you should contact the company maintaining your well for information on the installation of an appropriate filtering system. Normally, a Granular Activated Carbon (GAC) filter system can be installed to remove pesticides and other organic compounds. Monitoring the GAC filter system is necessary to maintain optimum filtering capacity via the replaceable carbon canisters.

The following links and contacts have been helpful to those interested in learning more about this topic:

Connecticut Department of Public Health Environmental Laboratory Certification Program In-State Approved Laboratories Certified to Test Drinking Water
http://www.ct.gov/dph/lib/dph/environmental_health/environmental_laboratories/pdf/InstateLaboratoriesCertifiedtoTest_DrinkingWater.pdf  

Agency for Toxic Substances and Disease Registry-Public Health Statement: Chlordane
http://www.atsdr.cdc.gov/PHS/PHS.asp?id=353&tid=62  

Agency for Toxic Substances and Disease Registry-Public Health Statement: Aldrin/Dieldrin
http://www.atsdr.cdc.gov/PHS/PHS.asp?id=315&tid=56  

Centers for Disease Control and Prevention:Water-related Diseases and Contamination in Private Wells
http://www.cdc.gov/healthywater/drinking/private/wells/diseases.html  

United States Environmental Protection Agency
The Incorporation of Water Treatment Effects on Pesticide Removal and Transformations in
Food Quality Protection Act (FQPA) Drinking Water Assessments
Office of Pesticide Programs, Washington, D.C. 20460 http://epa.gov/pesticides/trac/science/water_treatment.pdf  

Connecticut DPH-Environmental Health:
Sheree Rusnak (860) 509-7740 email sharee.rusnak@ct.gov  

Connecticut DPH-Well Water:
Ray Jarema (860) 509-7321 email raymond.jarema@ct.gov  

Connecticut Department of Environmental Protection:
Amanda Flad(860) 424-3351 email amanda.flad@ct.gov  


Please feel free to contact New Canaan Health Department at 203-594-3018 if further assistance is needed.

Briggs Geddis, RS Director of Environmental Health 
 
David M. Reed, MD, MPH Director of Health and Medical Director