Parts of a Water Well

As any dug, driven, or drilled hole in the ground for the use of extracting groundwater in underground aquifers, water wells have shown to be very useful throughout history. For the past 8,000 years, humanity has been using this method to provide water for up to entire villages at a time. Since then, the process and layout of the water well has been made much more streamlined and efficient.

In owning, operating, and maintaining a private water well, it is important to understand the different components that it is made up of. See the diagram to the right for an outline of a water well system and read below to learn more about each part:


  • Well Cap
    While lying on top of the well casing, the well cap exists so debris, insects, or small animals can’t find their way into the well system. Usually made of aluminum or thermoplastic, the well cap also comes with a vented screen so that the pressure difference inside and outside are equalized when water is pumped through the well.
  • Well Casing
    The well casing is characterized as a tubular structure placed in the drilled well in order to maintain the well opening. The purpose of this part is to confine the groundwater to its zone underground while preventing contaminants from mixing with the water. Carbon steel, plastic (usually PVC), and stainless steel are the most common materials for well casings while geologic formations and the depth of the well determine the casing material to be used. Consult your state/local governing agency for set laws that require a minimum length for casings.
  • Pitless Adapter
    The pitless adapter provides a sanitary and frost-proof seal between the well casing and the distribution water line delivering potable water. After determining the frost line, the adapter is connected to the well casing below the frost line. Water from the well is then diverted horizontally at the adapter to prevent it from freezing.
  • Distribution Line
    The distribution line delivers potable water to the consumer from the well. The most popular types include galvanized steel, copper, and plastic.
  • Bentonite Grout
    Bentonite grout is applied in order to maintain and protect the water quality of an aquifer. This filler also prevents contamination from the surface or the commingling of waters from different aquifers. 
  • Drop Pipe
    The drop pipe connects the submersible pump and carries the well water to the well head. It normally consists of threaded lengths of galvanized steel or plastic or one continuous length of flexible plastic. The importance of the load bearing capacity of the drop pipe is directly proportionate to the depth of a well.
  • Pump
    Water well pumps are installed in order to remove and/or transfer water from a water well. The most common water well pumps include:
    • Submersible pumps – Most commonly used in drilled wells
    • Jet pumps – Compatible with shallow wells
  • Well Screen
    The well screen attaches to the bottom of the casing and is defined as an optional filtering device used to prevent excess sediment from entering the well. The most popular screens are continuous slot, slotted pipe, and perforated pipe.
  • Gravel Pack
    The gravel pack increases the water well’s production by increasing the well’s surface area. It can be used by itself or in combination with a well screen. The pack itself is a downhole filter designed to prevent the introduction of unwanted formation sand.


The basic parts of a private water well, when combined with a pump, provide potable water for a household or structure. Whether you’re a homeowner, pump manufacturer, well driller, supplier, or distributor – no matter what part you play in the private water well application – you can always benefit from knowing what every component is and does to the system!

To learn more about the topic, take our 'Parts of a Water Well' AYU course.