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Glossary: Well, Well Pump, and Simple Pump Terms

November 27, 2023
5 min read

These are brief descriptions only and are intended for someone not very familiar with well and pump terminology.

General Well Terminology

Dug Well

Usually old wells or in developing nations. A hole is hand dug in the ground and lined with solid material such as brick, rocks or concrete culvert. These days, an excavator is sometimes used, a section of culvert put into place, and the hole filled.

Bored Well

Typically 2′ or 3′ wide, although can be wider. Used when low yielding groundwater sources are found relatively close to the surface. Typically less than 100′ deep. Because the water source is low yielding, the wide well provides a reservoir. Typically drilled using a “rotary bucket auger”.

Drilled well

Typically 4-8″. A hole is drilled that will be a little larger than the casing. The casing is installed and the hole back-filled. Generally has the advantages of:

– Being less susceptible to pollution from surface sources because of the depth.

– And being a more reliable water supply, since it is less affected by seasonal weather than a shallow well.


The metal or PVC pipe that lines your well. Commonly 4, 5, 6, or 6.25 inches inside diameter. Sometimes 2, 3, 4.5, 7 or 8 inches.

The casing of a bored well (see above) will often be concrete.

Sleeve and Liner

Some wells have a narrower casing for most of their depth and a wider section near the top — maybe the last ten or twenty feet. The wider part is the sleeve. The narrower part is the liner.

Static Water Level or Water Level or Static

The distance from ground level down to the water at its stable level (i.e. not during or just after pumping).

Well Pumps and Associated Hardware


The position of the pump in the well. E.g. “the submersible is set at one hundred feet” or “The submersible set is one hundred feet”. Both mean the submersible is one hundred feet down in the well.

Pump Head

The part of the pump that is visible above ground.

Well Caps and Seals

Well CAPS fit over the top of the casing similarly to how a jam jar lids fits over the top of a jar. There is overlap down the side. Bolts hold the cap to the casing.

Well SEALS consist of metal plates that sandwich a layer of rubber. As the plates bolts are tightened, lessing the distance between the plates, that rubber seal pushed out against the inside of the well casing, and inwards around the outside of the pump discharge pipe.

These two terms, cap and seal, are sometimes used interchangeably. We like to keep the distinction as described above. All our well caps are well CAPS.

Pitless Adaptor

A pitless adaptor clamps to the side of the casing, and routes the water out through the side of the casing to run underground.

The submersible drop pipe comes up from underneath and attaches to the bottom of the pitless adaptor. Part of the pitless extends through a hole is the side of the casing where (typically) a lock nut then clamps it in position.

A horizontal pipe attached to the pitless outside the casing and carries the water to the home.

The “pitless” part of the name refers to the fact that these adapters did away with the older style of wells that used “pits”. A pit might be three or six feet wide and four or eight feet deep. The narrower well would then be in the floor of the pit. These had several disadvantages:

  • Could be dangerous for children
  • Could accumulate water leading to severe rusting and possible contamination
  • Could house rodents
  • Were inconvenient for servicing
  • Were not as secure against frost.

On all these counts, a pitless adapter configuration is much superior compared to old-style pits. Simple Pump has its own pitless adaptor, a reengineered Merrill 50.

Pitless/Turtle/Clamshell well caps

This is a particular type of well cap used only with a pitless setup. There is no provision for the submersible pipe to exit through this type of well cap, since it goes out through the side of the casing. The shape is mostly a circle with a bumpout on one side. The electrical wiring is routed through that bumpout and usually runs in a conduit down the side of the casing.

The turtle and clamshell names refer to to the fact that there are two halves with a space between.

Drop Pipe

Drop pipe is the pipe that runs from the top of the well down to the pump. The three materials more commonly used in domestic wells are steel, PVC and high density polyethylene. Simple Pump uses PVC pipe certified for drinking water application, with stainless steel couplers.

Pressure Discharge

The water being pumped from the submersible is under pressure. The pipe carrying the water out of the well is, therefore, sometimes referred to as the “pressure discharge” or “submersible discharge”.

A pump’s discharge can either be through a pitless adaptor, or up through the well cap.

Check Valve

A valve allowing water flow in one direction only — towards your house.

Coupling/coupler/butt coupler

The coupler joins each length of submersible drop pipe. Steel or PVC are most common. Brass and galvanized couplings are sometimes used.

Center Guides

Plastic or rubber devices, sometimes used, that slip over or snap onto the drop pipe, centering it in the well casing, and holding the electrical cable close to the pipe.

Torque Arrestor

A flexible rubber or PVC device that may be mounted on the drop pipe a few feet above your submersible to prevent the pump from kicking with start-up torque.

Submersible Pump

An electrically driven pump situated in the water in a well. Pushes the water to the surface.

Jet Pump

The motor of a jet pump is situated above ground level. It pumps water through a narrow jet, creating a pressure differential that draws more water in and back to the surface.

Foot Valve

The name for the water inlet valve at the bottom, on some types of hand pumps.

Simple Pump Terminology

Seal Kit

A package of seals for the Simple Pump: two for the pump head, either two or three for the pump cylinder.

Safety Tool

A U-shaped piece of machined aluminum with a bevelled seat. The coupler on our drop pipe sits securely on the safety tool during installation.

T-Handle installation tool

Screws into the top end of the topmost drop pipe for even more secure handling of longer assemblies of drop pipes.

Pedestal Adaptor

A flat plate with a circular rim on which can be mounted a 4″ well cap. Used to mount the Simple Pump on the wood, metal or concrete cover of a wide well, when a submersible pipe also needs to be accommodated.

Mounting Plate

A flat plate with split flange to hold the Simple Pump. Used to mount the Simple Pump on the wood, metal or concrete cover of a wide well. Used when a submersible pipe does not have to be accommodated.

Drop Pipe Kit

A “drop pipe kit” consists of our drop pipe plus the sucker rod that runs inside it plus a rod guide.

Sucker Rod

The rod inside the drop pipe that provides the mechanical connection between the handle or motor at the top and the piston inside the pump cylinder at the bottom.

Rod Extenders

A 1.25″ x 3/8″ steel extender for possible fine-tuning of the total length of the chain of lift rods.

Weep Hole

1/16″ hole drilling at 4′ or custom length down the top drop pipe. After the pump is used, the weep hole allows water to drain out of the pump head, preventing freezing — or, in very hot climates, over-heating.

Pump Cylinder

Situated at the bottom of the system, at the end of the chain of drop pipes. With a piston and two valves, this is where the action happens, to lift your water to the surface.