Wells, What You Need to Know
Basic Information About Drinking Water Wells
Private drinking water wells are typically shallow (less than 200 feet deep). They are often constructed from solid steel or heavy plastic well casings with screens to allow water to enter. They often contain below-grade water line connections to prevent freezing.Over 15 million U.S. households (approximately 15 percent of Americans) rely on private wells for drinking water.
Proper well construction and continued maintenance are keys to the safety of your water supply. Your state water-well contractor licensing agency, local health department, or local water system professional can provide information on well construction.
Well drillers and pump-well installers should be bonded and insured. Make certain your ground water contractor is registered or licensed in your state, if required, and preferably certified.
For more information refer to your local health department for permitting and water quality testing information
Types of wells
There are three types of private drinking water wells.
- Dug wells are holes in the ground dug by shovel or backhoe and are typically lined (cased) with stones, brick, tile, or other material to prevent collapse. Because dug wells are typically shallow (approximately 10 to 30 feet deep) they have the highest contamination risk.
- Driven wells are hammered or hydraulically pushed into the ground and pull water from the water-saturated zone. Driven wells are also shallow (approximately 30 to 50 feet deep) and have a moderate-to-high risk of contamination from nearby land activities.
- Drilled wells are deeper (approximately 100 to 400 feet) and typically have metal or plastic pipe casing which protect the well water from sources of contamination. Drilled wells have a lower risk of contamination. However, no well can be assumed to be contamination-free.
Keeping your well safe
To keep your well safe, be aware if any possible sources of contamination are nearby. Check with your local health department or environmental program for setback requirements.
Tips for keeping your well safe:
- Maintain your well, find problems early and correct them to protect your well’s performance.
- Keep up-to-date records of well installation and repairs, plus pumping and water tests.
- Protect your own well area. Be careful about storage and disposal of household and lawn care chemicals and wastes.
- Take steps to reduce erosion and prevent surface water runoff.
- Regularly check underground storage tanks that hold home heating oil, diesel, or gasoline.
- Make sure your well is protected from the wastes of livestock, pets, and wildlife.
Human Health and Contaminated Water
Naturally sources of contamination
- Microorganisms are bacteria, viruses, and parasites sometimes found in water. 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.
- Nitrates and nitrites are inorganic compounds usually created from human activities, but may also be found naturally in groundwater. 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 formula-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, and 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.
Contamination from human activity
- Bacteria and nitrates: These contaminants are found in human and animal wastes. Septic tanks, sanitary landfills, garbage dumps, large numbers of farm animals, and fertilizers can cause bacterial and nitrate pollution. Both septic systems and animal manures must be carefully managed to prevent private well contamination.
- 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 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: Fertilizers and pesticides are used to promote growth and reduce insect damage in agricultural practices, home gardens, and lawns. Many fertilizers contain forms of nitrogen that can break down into harmful nitrates, as well as phosphorus which promotes algae growth.
- Industrial products and wastes: Many harmful chemicals are used widely in local business and industry. 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 and can corrode with age. Tanks are often found on farms. The possibility of leaking tanks is great on old, abandoned farm sites.
- Landfills and waste dumps: Modern landfills are designed to contain any leaking liquids, but floods can carry contaminants 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 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.
Information on the page originally posted by US EPA at https://www.epa.gov/privatewells.