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• Natural sources of contamination
• Contamination from human activity

Naturally sources of contamination

The first step to protect your health and the health of your family is learning about what may impact the quality of your source of drinking water.  

• Microorganisms are bacteria, viruses, and parasites sometimes found in water. Shallow wells are at greater risk of contamination. Runoff, or water flowing over the land surface, may pick up contaminants from wildlife and soils. This is often the case after a flood. These organisms can cause a variety of illnesses.
• Radionuclides are radioactive elements such as uranium and radium. They may be present in underlying rock and ground water. Radon is a gas that is a natural product of the breakdown of uranium in the soil and can also pose a threat. Radon is most dangerous when inhaled and contributes to lung cancer. Although soil is the primary source, using household water containing radon contributes to elevated indoor radon levels. Radon is less dangerous when consumed in water, but remains a risk to health. 
• Nitrates and nitrites are inorganic compounds. Usually from human activities, they may also be found naturally in ground water. They come from the breakdown of nitrogen compounds (such as fertilizers) in the soil. High levels of nitrates and nitrites in drinking water have a more significant health impact on fomula-fed infants.
• Heavy metals occur naturally in underground rocks and soils. Heavy metals from natural sources may be a concern in some areas, but are not often found in household wells at dangerous levels. Naturally-occurring heavy metals include:
  • Arsenic
  • Cadmium
  • Chromium
  • Lead
  • Selenium
• Fluoride: High levels of fluoride occur naturally in some areas and can contaminate private wells. Fluoride is helpful in preventing tooth decay; however, excessive consumption of fluoride can damage bone tissue. Too much fluoride can also cause tooth discoloration in young children.

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Contamination from human activity

Septic tanks are designed to have a “leach field” around them — an area where wastewater flows out of the tank. This wastewater can also move into the ground water.

• Bacteria and nitrates: These contaminants are found in human and animal wastes. Septic tanks or large numbers of farm animals can also cause bacterial and nitrate pollution. Both septic systems and animal manures must be carefully managed to prevent private well contamination.
  • ​Sanitary landfills and garbage dumps are also sources.
  • Children and some adults are at extra risk when exposed to water-born bacteria. These include the elderly and people whose immune systems are weak due to AIDS or treatments for cancer.
  • Fertilizers can add to nitrate problems.
    • Nitrates cause a health threat in very young infants called “blue baby” syndrome. This condition disrupts oxygen flow in the blood.
• Concentrated animal feeding operations (CAFOs): The number of CAFOs, often called “factory farms,” is growing. On these farms thousands of animals are raised in a small space. The large amounts of animal wastes/manures from these farms can threaten water supplies. Strict and careful manure management is needed to prevent pathogen and nutrient problems in private wells. Salts from high levels of manures can also pollute ground water.
• Heavy metals: Activities such as mining and construction can release large amounts of heavy metals into nearby ground water sources. Some older fruit orchards may contain high levels of arsenic, once used as a pesticide. At high levels, these metals pose a health risk.
• Fertilizers and pesticides: Farmers use fertilizers and pesticides to promote growth and reduce insect damage. These products are also used on golf courses and suburban lawns and gardens. The chemicals in these products may end up in ground water. The extent of contamination depends on the types and amounts of chemicals used and how they are applied. Local environmental conditions (such as soil types, seasonal snow, and rainfall) also impact their contamination potential.
  • Many fertilizers contain forms of nitrogen that can break down into harmful nitrates. This could add to other sources of nitrates mentioned above.
  • Some underground agricultural drainage systems collect fertilizers and pesticides. This polluted water can pose problems to ground water and local streams and rivers.
  • In addition, chemicals used to treat buildings and homes for termites or other pests may also pose a threat.
  • Again, the possibility of problems depends on the amount and kind of chemicals. The types of soil and the amount of water moving through the soil also play a role.
• Industrial products and wastes: Many harmful chemicals are used widely in local business and industry. These can become drinking water pollutants if not well managed. The most common sources of such problems are:
  • Local businesses: Factories, industrial plants, and even small businesses such as gas stations and dry cleaners handle a variety of hazardous chemicals that need careful management. Spills and improper disposal of these chemicals or of industrial wastes can threaten ground water supplies.
  • Leaking underground tanks and piping: Petroleum products, chemicals, and wastes stored in underground storage tanks and pipes may end up in the ground water. Tanks and piping leak if they are constructed or installed improperly. Steel tanks and piping corrode with age. Tanks are often found on farms. The possibility of leaking tanks is great on old, abandoned farm sites. Farm tanks are exempt from the EPA rules for petroleum and chemical tanks.
  • Landfills and waste dumps: Modern landfills are designed to contain any leaking liquids, but floods can carry conaminants over the barriers. Older dumpsites may have a wide variety of pollutants that can seep into ground water.
• Household wastes: Improper disposal of many common products can pollute ground water. These include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and detergents can harm drinking water. These are often a problem from faulty septic tanks and septic leaching fields.
• Lead and copper: Elevated concentrations of lead are rarely found in source water. Lead is commonly found in household plumbing materials. Homes built before 1986 are more likely to have lead pipes, fixtures, and solder. Lead can leach into water systems when these plumbing materials corrode. Your water’s acidity or alkalinity (often measured as pHpHThe measure of acidity or alkalinity of a chemical solution, from 0-14. Anything neutral, for example, has a pH of 7. Acids have a pH less than 7, bases (alkaline) greater than 7.) greatly affects corrosion. Temperature and mineral content also affect how corrosive it is.

Lead in drinking water can cause a variety of adverse health effects. Exposure to lead in drinking water can cause delays in physical and mental development in babies and children. Adults who drink this water over many years could develop kidney problems or high blood pressure.

• Water treatment chemicals: Improper handling or storage of water-well treatment chemicals (such as disinfectants or corrosion inhibitors) close to your well can cause problems.

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