More than 43 million people or 15% of the U.S. population rely on private wells for their water supply. While typically private water wells serve as a viable water source, if untreated or unfiltered, private water systems may contain contaminants. Water from private wells may contain different contaminants that could affect the health and wellbeing of both humans and animal.

To ensure your private water source is fit for consumption, it is important to have your well checked and tested annually for physical and biological contaminants. Because of the changes that can occur in an areas water table overtime, some private well sources may begin to experience contaminants that they may not have beforehand. A private well that was once tested should be tested again to ensure no changes have occurred making it unsafe.

Other water quality factors like pH and alkalinity should also be monitored in your private water source to ensure safe consumption.

At Weeks Drilling, our team of certified water treatment operators can provide your private well source with the best treatment solutions. To ensure you are practicing the best water treatment safety for your home and family, our team has compiled a list of the most common contaminants that you may find when using an untreated private water source.


Water from a private well can contain different types of biological contaminants including bacteria, and viruses. These microorganisms can cause a whole host of health problems if consumed untreated by both humans and animals.

There are several ways microbial contamination of private well water can occur. Runoff is one of the most common causes of water contamination. If a nearby underground storage tank or your septic leach field is leaking, microorganisms can enter your private well, contaminating your water.

Germs live and grow in pipes. If the pipes used for your private well have become a breeding ground for microbes, disease-causing bacteria and viruses can enter your water supply.

A common pathogen found in water from private wells is coliform bacteria. Coliform bacteria are naturally present in plants and soil. They are also found in the digestive tracts of warm-blooded animals.

If your well water tests positive for coliform bacteria, be sure to test it for fecal coliform bacteria as well. A positive fecal coliform test suggests that your water is contaminated with fecal matter, and is hence, unfit for consumption.

Most bacteria are non-hazardous contaminants, however, some strains of E. coli, a member of the coliform family, can cause serious gastrointestinal illnesses.


Metals are naturally occurring. Heavy metals used in household plumbing can leach into groundwater, making it unfit for consumption.

Mining and petroleum operations can generate large quantities of heavy metal lawn waste that is able to enter waterways and private wells, leaving them contaminated.

If a pipe carrying water from your private well to your house becomes damaged, heavy metals and harmful chemicals may also be able to enter your water supply.

Some dangerous heavy metals found in water from private wells include arsenic, lead, selenium, cadmium, copper, nickel, and zinc.


Radiological contaminants or radionuclides include radioactive substances such as plutonium, cesium, and uranium. Radiological contaminants can be naturally occurring or man-made.

Radiological contamination of water occurs when waste from different industries such as construction, mining, oil and gas exploration, and fertilizer gets in it.

Other sources of radiological contaminants include waste from nuclear power plants and medical waste. When radioactive waste is stored or disposed of improperly, radioactive particles in it can seep into groundwater, polluting nearby rivers, streams, leaks, and private wells. Radionuclides are naturally present in groundwater in some areas.

Physical Contaminants

Some common physical contaminants that may be found in a private water supply include debris, sediment, dust, and organic material.

These types of contaminants usually affect the appearance or physical properties of water. Consumption of sediment polluted water can pose a risk to human and animal health.

Organic Chemicals

Organic chemicals are found in organic solvents, paints, dyes, pesticides, disinfectants, petroleum products, household cleaners, and degreasers.
Runoffs and spills can allow organic chemicals to enter your water supply. Long-term exposure to organic chemicals can cause kidney damage. Organic chemicals can also affect the reproductive system, circulatory system, and nervous system.

Tips to Protect Your Private Well from Contamination

  • Choose well site wisely: If you are drilling a new water well, make sure the location chosen is best suited for drawing ground water. When deciding the best location for your new water well, consult a professional and they will help you determine the optimal location. Keep in mind elements on your property that might pose risk of contamination like septic systems, irrigation systems, and other underground infrastructure. When consulting with a well drilling company, be sure to include discussing these elements to help them determine the best solution for your new well.
  • Use the right well casing: When choosing a well casing, refer to the specifications developed by the American Society for Testing and Materials, the American Iron and Steel Institute, and the American Petroleum Institute. A professional well drilling company will know the specifications needed to ensure safety and requirements for your private well system.
  • Maintain your well: Periodically check the well cover or well cap to make sure it is not damaged. Maintain proper separation between your well and waste systems and chemical storage facilities. Schedule a professional well inspection and maintenance at least once every year. Keep maintenance records
  • Be careful when landscaping around your well: Be very careful when mowing around your well or you may inadvertently damage its casing. Do not pile debris such as leaves around your well. Store, mix and spray fertilizers as far away from your well as possible

Weeks Drilling & Pump Co. is one of the oldest and most trusted groundwater firms serving Napa, Sonoma, Marin, Mendocino, and Lake Counties. Our ability to tailor solutions to our client’s needs is what sets us apart. To learn more, call (707)823-3184.