Groundwater protection

As the term suggests, there is much from which groundwater needs to be protected. Any hazardous substance—if spilled on the ground, leaked underground, or poured down an abandoned well or borehole—can infiltrate groundwater, the drinking water source for nearly 35 million Americans using privately owned water wells.

As a private well owner, you are the manager of your water system. Your practices as a property owner can directly impact your water quality or that of other well owners in the area. A little education in groundwater protection goes a long way.

Groundwater protection questions:

How is groundwater quality threatened—and what can I do to protect it?

Some issues that adversely affect the quality of groundwater for drinking water purposes are beyond the control of the well owner. For instance, arsenic and radon can occur naturally in the geology and therefore be present in groundwater used by wells. Also, some manmade contamination—for example, from a leaking landfill or an industrial site—cannot be managed by an individual well owner.

However, there are other practices within the control of a well owner that can protect groundwater from contamination, such as:

  • Proper storage and disposal of hazardous substances such as herbicides, pesticides, fertilizers, paint, and petroleum products to name a few
  • Making sure your well has a properly designed, installed, and maintained well cap
  • Using a water well professional to plug any abandoned wells or boreholes on your property
  • Keeping a sufficient distance between your wellhead and other potential contamination sources such as roads, buildings, septic system drain fields
  • Not disposing of hazardous substances in a septic system.

Learn more about groundwater protection here.

What is the most common threat against which I can protect my groundwater?

The most common threat to groundwater within your control is disease-causing bacteria. These microorganisms are abundant in the natural environment.

A properly located, constructed, and maintained water well system is designed to keep microorganisms out of your well system.

Learn more about groundwater protection here.

How can I protect my drinking water from harmful bacteria?

Two actions well owners can take to protect their drinking water from bacteria are to (1) make sure there is no pathway for microorganisms to enter your well system, and (2) keep your well away from any concentrated source of bacteria.

1. Well system maintenance: A properly constructed well system has various sanitary seals starting with the well cap. The well cap should:

  • Be bolted or locked so that it cannot be tampered with or jarred loose
  • Be watertight and resistant to rain, sleet, snow or ice
  • Have a rubber seal with the well cap, where it adjoins the well casing
  • Not be cracked or otherwise broken.

In areas where freezing occurs, a “pitless adapter” is another sanitary seal that prevents bacteria from entering the well where the water distribution pipe located below the frost line connects to the well.

There also is a sanitary seal at the electrical conduit connection, where the electrical conduit containing wiring for a submersible pump connects to the well.

The well casing—the vertical pipe that goes down into the well—also is a sanitary seal which, in addition to keeping the borehole open—prevents surface water and shallow groundwater from prematurely entering the well.

Another sanitary seal is the specialized well grout that fills the space between the outside of the well casing and the inside of the borehole to prevent surface water from infiltrating the well.

2. Separation from contamination sources: Many states and localities specify separation distances between a well and contamination sources. Separation distances in your area may take into consideration the local geology, which can affect the susceptibility of groundwater to surface contamination.

The following minimal distances should be maintained from the wellhead, unless other state or local codes or regulations prescribe more stringent standards:

  • Cesspool (receiving raw sewage), 200 ft.
  • Pit, privy, filter bed, 50 ft.
  • Septic tank, tile sewer, foundation drain, 50 ft.
  • Iron sewer with approved mechanical joints, 10 ft.
  • Pumphouse floor drain, 2 ft.
  • Property boundary, 5 ft.
  • Outer boundary of any road, 20 ft.
  • Landfill, garbage dump, 200 ft.

Learn more about groundwater protection here.

Do I need to worry about my septic system polluting my drinking water?

A properly located and maintained septic system can be an effective way to treat household sewage.

However, if the septic system is not located in an appropriate place in relation to your well or the septic system is not maintained, it could contaminate the groundwater you or other well owners consume. It is wise for well owners to test the drinking water annually for bacteria or when family or guests are experiencing recurring incidences of gastrointestinal illness.

To learn about the proper location and maintenance of a septic system, one type of onsite wastewater recycling system, visit the National Onsite Wastewater Recycling Association.

Learn more about groundwater protection here.

What are common ways that bacteria get into a well?

Two of the most common ways that bacteria get into wells are through a defective well cap or through improperly abandoned wells.

Well caps: Not just any covering will do on top of the well casing, that vertical pipe that extends above the ground in your well. A proper well cap should be:

  • Bolted or locked, so that it cannot be easily removed
  • Fitted with a rubber seal to prevent vermin from infiltrating the well where the cap is joined to the well casing
  • Watertight
  • In good condition.

Conversely, a tight-fitting well cap that is not bolted or locked can be jarred loose or removed by someone other than the well owner. Also, a well cap that lacks a rubber seal or is cracked or otherwise broken can allow bugs, vermin, bacteria or other types of contaminants above the ground surface into the well.

Well caps should be installed by a water well system professional, and any well cap maintenance or replacement should be done by a professional. Also, a well system should be disinfected when a well cap is installed, repaired, or replaced.

Abandoned wells: First, the challenge is sometimes to find abandoned wells on your property. Some abandoned wells are obvious while others are not. Survey your property for:

  • Pipes sticking out of the ground
  • Small buildings that may have been a well house
  • Depressions in the ground
  • The presence of concrete vaults or pits
  • Out-of-use windmills.

Other tips for finding old, abandoned wells can be found in:

  • Old maps, property plans or property title documents
  • Neighbors
  • Additions to an old home that might cover up an abandoned well.

A water well system professional may do additional checking—including a records check—for more information about abandoned wells.

A water well system professional should always plug an abandoned well using proper techniques, equipment, and materials. The professional should:

  • Remove all material from the well that may hinder proper plugging
  • Disinfect the well
  • Then plug the well using a specialized grout that (1) keeps surface water from working its way into the borehole, and (2) prevents water from different levels in the subsurface from mixing.

The cost to plug a well depends on factors including:

  • The depth and diameter of the well
  • The geology of the area
  • Accessibility to the well, and
  • The condition of the well.

Learn more by watching this video.

Flooding has happened in my area. Does flooding on the surface affect my well water?

While not a certainty, it is possible for surface flooding to affect well water. Well construction and where the wellhead is located can affect how susceptible a well is to flooding. Consequently, well owners should determine their wells’ possible vulnerability to flooding.


  • Check the general condition and whether the casing extends at least 12 inches above ground. If it is in a flood-prone area, the casing may need to be extended above the historic flood level.
  • Generally, the well casing is best located on relatively higher ground to minimize the pooling of surface runoff around the well casing. Be sure the ground surrounding the wellhead is sloping away from the well to divert surface runoff. If there is no concrete pad surrounding the well casing, contact your local health department or regulatory agency to determine if one should be installed by a water well system professional.

Well cap (cap on top of casing)

  • Check the condition of the cap and any seals, and that it is securely attached.

In the event of flooding

After a flood, the owners of household wells should take certain precautions to make sure their water is safe and their well is in good operating condition. An obvious concern is that flood water loaded with bacteria, chemicals, or other pollutants may have gotten into the well or area groundwater. A less obvious concern is electrical shock if a non-submersible pump or any part of the well electrical system is flooded.

After a flood one should:

  1. Stay away from the well pump while it is flooded to avoid electrical shock
  2. Not drink the water from the well or use it for washing to avoid becoming sick
  3. Get help from a water well system professional or pump installer to:
  • Clean and turn on the pump
  • Flush the well
  • Disinfect the well
  • Perform any other necessary maintenance.

Next steps

If you find any potential maintenance issues, consult with your water well system professional. To find a water well professional, click on

You may find other water well system professionals (1) in your local Yellow Pages, (2) by asking other water well owners what professional they use or recommend, or (3) by asking the person in your state who oversees the licensing or registration of water well professionals, using contact information at

Water wells are specialized systems that require knowledge and expertise to repair and disinfect. If your well has been flooded, use bottled water or boil your water until a water well system professional can check out your well system. Well owners also can benefit from reading the well maintenance and water quality sections of this website.

Learn more about groundwater protection here.

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Well construction
Well system maintenance
Water testing
Water treatment