Submersible Well Pumps for Drinking Water Wells
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Refer to this rough sketch of a deep well with a submersible pump. This list and definition of water well parts and terms is organized from the top of the drawing towards its bottom and uses names that correspond to those shown in our drawing. First we describe items listed on the right side of our sketch, second we describe items and terms listed on the left side of the sketch.

Definitions of well and water pump items shown on the sketch right side, top to bottom:

• Well cap which you can see at the top of the sketch as well as in the photographs just above, is a seal intended to keep surface runoff and debris out of the well casing. Many well caps are not water tight, which is why modern drilled well casings extend above ground level.
• Wiring to the well pump is sketched entering at the well cap and is also visible as the gray conduit in the above left hand photo of a well casing. When this wiring is visible we know that the pump is in the well and therefore a submersible pump is installed. If this wiring is absent we expect to find that the well pump is either nearby in a well pit or is located inside the building it serves.
• Pitless Adapter is the special fitting that seals the hole in the well casing where the water piping makes its right angled turn and then exits the well casing to pass on to the building.
• Water piping to the house rises vertically inside the well casing from the top of the submersible pump to a point (below the frost line in cold climates) where it makes a right angled turn and passes out through the well casing and onwards to the building.
• Well casing is in this sketch the 6" diameter steel pipe which is driven into the well from above ground into bedrock, then sealed against groundwater leaks.
• End of Casing marks the point at which the well casing (usually about 6" diameter steel pipe) has extended into bedrock and has been sealed. The remainder of the hole drilled to form the water well is drilled (usually) through water bearing rock.
• Water flow through cracks in rock is shown in the drawing, indicating that water enters the well by flowing through multiple fissures in the water bearing rock. (We don't usually tap right into an underground lake or stream of water though that's possible in some areas.)
• Water Pump, in this case a submersible water pump since it's inside the well, is located near but somewhat above the very bottom of the well.
• Well recovery rate or well water flow rates (marked as R1, R2, R3) indicate that water actually flows into the well at different flow rates from different rock fissures at different depths in the well. The well flow rate is the sum of all of these water in-flows, measured in gallons per minute that water flows into (or can be drawn out of) the well over a standard measurement period, usually 24 hours. So a 5 gallon per minute yield well indicates that the water flow into or recovery rate of the well is the same as the rate at which we can draw a sustained water flow out of the well for some time period.
• Pump Clearance from Bottom shows that the water pump is inserted into the well some distance from the very bottom of the well (inches to a few feet). We need this clearance to reduce the tendency of the well pump to pick up mud and debris from the bottom of the well.

• Ground level marks the actual ground surface level in the sketch. Note that the well casing extends above ground level to avoid surface runoff entry into the well (where it would contaminate the well water and local aquifer).
• Air (a) marks the distance from ground level extending down inside the well casing which is filled with air. Except in cases of artesian wells, the at-rest level of water in a drilled well is always some distance between the ground's upper surface. This is one of the reasons that knowing the "depth of a well" from ground level to well bottom does not tell us how much water is inside the well casing.
• Water Top (WT) marks the level to which water rises inside the well casing when the well is at rest (not in use). This level often varies seasonally, dropping lower in dry seasons and rising during the rainy season. (WT) marks the very top of the amount of water which is available to the water pump when it is turned on to send water out of the well on to its destination.
• Slurry shows the slurry which is pumped around the outside of the well casing after the casing has been inserted into the drilled well opening. The slurry acts to seal the well casing against surface water entry and contamination.
• Bedrock shows that for a typical drilled water well, the lower portion of the well, below the end of the well casing, is a hole drilled into bedrock.
• Rock fissures and recovery rates R1, R2, R3 indicate that water actually flows into the well at different flow rates from different rock fissures as we discussed just above where we explained well recovery rate.
• Well Depth (d) is a vertical arrow showing that the total drilled depth of the well is the distance from the ground surface to the very bottom of the well. Well depth is also the sum of Air (a), Static Head (h), and Pump Bottom Clearance (c).
• Static Head (h) is the height of the total column of water which is available to the water pump to draw on inside the well. This amount or vertical distance inside the well extends from the very bottom of the well pump itself to the at-rest top of the water column in the well. Inside a 6" diameter well casing we find about 1.5 gallons per foot of height of the column of water.
• Pump Clearance from Bottom of Well (c) as we mentioned earlier, shows that the water pump is inserted into the well some distance from the very bottom of the well (inches to a few feet). We need this clearance to reduce the tendency of the well pump to pick up mud and debris from the bottom of the well.