How to Control the Quality of Water from Your Well

In the U.S., more than 15 million households depend on private ground water wells. These well owners enjoy control of quality of their water. Wells are usually low maintenance, but every once in a while groundwater or well water becomes contaminated or saturated in minerals that can affect the smell and taste of the water.

How Wells and Groundwater Work Together

When rain falls, much of it is absorbed into the ground. Plants then use as much of the water as they can for growth and nutrients. What isn’t used by plants seeps further into the ground through pores and spaces in the rock. Eventually the water reaches a dense layer of rock and pools. Water trapped below the ground in the pores and spaces above the dense rock barrier is called ground water, and this is the water we get as drinking water when we drill wells.

What Endangers Well Water Quality

Obviously, if polluted groundwater is consumed, it could make you sick. Groundwater pollution can be caused by seepage through landfills, failed septic tanks, underground fuel tanks, fertilizers and pesticides, and runoff from urban areas. (Just reading that is enough to make you sick.)

How and When to Test Your Water

Unlike city or municipal utilities, groundwater for home use is not regulated by the Environmental Protection Agency (EPA). To maintain the safety and quality of your well water, it is important to check your well water regularly to ensure the water is safe for drinking.

The National Ground Water Association (NGWA) recommends well owners test their water at least annually for bacteria, nitrates, and any contaminants of local concern. More frequent testing should be considered if:

  • There is a change in the taste, odor, or appearance of the well water, or if a problem occurs such as a broken well cap, inundation by floodwaters, or a new contamination source
  • The well has a history of bacterial contamination
  • The septic system has recently malfunctioned
  • Family members or house guests have recurrent incidents of gastrointestinal illness
  • An infant is living in the home, or
  • To monitor the efficiency and performance of home water treatment equipment.

To test your water you can call a licensed contractor or you can take a sample of your water to your local pool supply store, local health or environmental department or your local agriculture extension service. These organizations can also tell you what type of soil you have and what tests to use as well as what contaminants or minerals are often found in the local area.

Common Contaminants and Their Causes

The NGWA and provide the following information on contaminants:

Total coliform are a broad category of bacteria, most of which pose no threat to humans. Some come from fecal matter; others naturally occur in soils, vegetation, insects, etc. Total coliform is the most commonly used indicator of bacterial contamination. The presence of coliform bacteria is an “indicator” of a well’s possible contamination from human or animal wastes.The presence of coliform bacteria in well water can be a harbinger of worsening water quality. In some cases, more specific tests for fecal contamination, such as E. coli, may be used.

Common sources of nitrates in well water are fertilizers, septic systems, animal manure, and leaking sewer lines. Nitrate also occurs naturally from the breakdown of nitrogen compounds in soil and rocks. High levels of nitrate in well water present a health concern and can also indicate the presence of other contaminants, such as bacteria and pesticides. Drinking large amounts of water with nitrates is particularly threatening to infants.

Ask about additional tests for pH, hardness, iron, manganese, sulfides, and other water constituents causing problems with plumbing, staining, water appearance, and odor. Changes in these constituents also may indicate changes in your well or local groundwater. Additional tests may be recommended if water appears cloudy or oily, if bacterial growth is visible on fixtures, or water treatment devices are not working as they should.

To find a certified water testing laboratory in your area, contact your state certification officer by visiting the U.S. EPA Web site at

  • Newsletter sign up

    • Sign up for our quarterly newsletter full of tips and information for homeowners.
  • Join the Conversation!

  • Links to great resources

  • Call Us

    Well Care Hotline:

    Monday through Friday from 10:00 a.m. to 5:00 p.m.
    The wellcare® Hotline is a free, friendly service that can answer questions on wells and well water