Groundwater Info Center
Well Basics

Figure 1. Three well construction methods.

How are wells constructed?

Construction of a water well begins with making a hole, using one of the three methods shown in Figure 1. Read about each method and watch videos of the most common drilling methods at

As the hole is excavated, the licensed well driller logs the depths at which water is produced. This information is used to design the well.

Figure 2. An example of typical well construction.
Source: State Water Resources Control Board,
March 2015

Figure 2 is an example of typical water well construction. The well "casing" is a metal or plastic pipe that is centered in the hole. The "well screen" is the perforated section of casing adjacent to the the water-bearing zone (aquifer). The remainder of the casing is "blank" with no perforations. Once the casing is inserted, a "filter pack" of sand and/or gravel is placed around the well screen to filter fine soils from water entering the well. The rest of the annular space, between the hole and the blank casing, is sealed with highly impervious materials to prevent contaminants from flowing through the annular space. Finally, the well is completed when the pump is placed and the wellhead features are constructed, including a concrete pad which slopes aways from the well.

To learn about principles of effective well construction, refer to Water Well Design and Construction (UC Davis with the Natural Resources Conservation Service, 2003).

How do I protect my water well?

Proper design and construction are key to a well's success. The well should be carefully located to minimize potential for contamination, away from septic systems and other pollutant sources. The annular space should be sealed with materials that meet statewide minimum well standards and local well ordinance requirements.

Simple preventative measures can ensure your well water stays clean:

Properly seal abandoned wells! Abandoned wells can act as vertical pathways for pollutants to enter the groundwater. They also pose a threat to public health and safety - children, animals, or even adults can fall into abandoned wells, causing injury or death. Well Decommissioning...There's a Plan for That (video, 3:18 minutes) by the Natural Resources Conservation Service of California provides important information for all landowners to recognize and address abandoned wells - with footage from an actual well destruction in Sacramento County. If you know of, or suspect an abandoned well, contact your local enforcing agency.

Resources for Private Well Owners


Local and Regional Resources

    Well Permitting Agencies are the local agencies responsible for issuing well construction, modification, and destruction permits.

    Groundwater Sustainability Agencies are the local/regional agencies being formed under the 2014 Sustainable Groundwater Management Act to manage groundwater.

    Regional Water Quality Control Boards are responsible for developing basin plans for their hydrologic areas, issuing waste discharge permits, taking enforcement action against violators, and monitoring water quality.

State Resources

National Resources