Water Well Components

Here you will find the 5 most popular water well components [well system components]

Well Casing

Well casing is basically the tubular structure that’s placed inside the drilled well to help maintain the well opening right from the target groundwater up to the surface. Along with the grout, it keeps excess or less desirable groundwater out of the well and also holds back the unstable earth materials/dirt so that they don’t collapse into the well.

They help prevent contaminants from entering the well and mixing with the water. The casing, in particular, ensures that the water is only drawn from the desired/targeted groundwater source (the bottom part where the well screen is attached). Some states and even local governing agencies have laws which require minimum lengths for a casing.

With regards to the materials for the well casing, the most common ones are carbon steel, stainless steel, and plastic (not exclusively PVC). Local geology and groundwater quality will often dictate the type of casing that can be used. For instance, steel casings are used in areas/states where hard rock lies underground while residents in other areas may use either steel or PVC, both of which have their own advantages and disadvantages.

Steel, for example, is strong and resistant to heat, but it costs more than PVC, plus it’s prone to corrosion and can have scale build-up. PVC, on the other hand, is cheaper, lightweight, and resistant to corrosion. It’s also fairly easy for contractors to install. It’s, however, not strong and resistant to heat like steel. Other contractors also use fiberglass, concrete, and asbestos cement casings.   

Well Cap

A well cap is a cover that’s placed on top of a well casing which sticks out of the ground. It’s usually made of a thermoplastic or aluminum material and serves many purposes. Its main function though is to prevent contaminants from getting into the well. Its inner gasket compresses to the outside diameter of the well casing thereby providing a watertight seal that keeps small animals, insects, or debris out of the well.

The caps also often have a vented screen that helps equalize the pressure difference inside and outside the well casing when water is being pumped from the well. Their top comes out easily to provide access to the well for service. Both the casing and the cap extend at least twelve inches above the ground and if the well is dug near a stream or river, they are at least extended past the flood level in order to keep overflows from contaminating the groundwater.

Well Screens

Well screens are filtering devices attached to the bottom end of the casing to help prevent too much sediment from getting into the well. They are made of either perforated pipe or continuous slot, slotted pipe – they allow the water to move freely through the well, while at the same time keeping out most of the gravel and sand.

A perforated pipe is basically a length of casing that features slots or holes drilled into the pipe, often once the casing is installed, perforated in place. It has wide openings which generally make it not quite efficient for aquifers that have a lot of gravel and sand. 

Continuous slot screens (slotted pipe screens), however, consist of plastic or wires wrapped around several vertical rods. They usually feature machine-cut slots into plastic or steel casing at set distances. This configuration ensures consistent, regular slot openings which can be engineered according to the size of the particles found in the screened zone. They have the least amount of openings making them ideal for aquifers with excess gravel and sand.

 Pitless Adapters

A pitless adapter is a connector installed in the casing just below the frost line. It allows the pipe that carries the well water to the ground surface to remain right below the frost line so as to prevent freezing.

Once the frost line for the place where the well is being set up is determined, the pitless adapter is then connected to the well casing just below the frost line. From there, water from the well is diverted horizontally at the adapter in order to prevent it from freezing.


A well pump is basically a machine that’s capable of moving, lifting, or raising water from a tank or well to the surface or other higher elevation or distant location.  It can create pressure and/or increase the velocity of the water. The two common types of well pumps are jet pumps and submersible pumps. 

Jet pumps are commonly used on the surface mostly for shallow wells (25 feet deep or less). They are mounted above ground and utilize suction to draw/pump water from the well. 

Submersible pumps are normally installed inside the well casing and are mostly used for deep private wells. The main pumping unit is set inside the well casing and then to a power source located on the surface. Other notable components of a well include the pressure tank and ball valve.