Water Well Driller key terms

Impermeable material, usually cement grout or bentonite, placed in the space between the borehole wall and the casing to block water and contaminants from moving along the outside of the casing.

A well that penetrates a confined aquifer under enough pressure that water rises above the top of the aquifer, sometimes flowing at the surface without pumping.

A long cylindrical bucket with a check valve, lowered on a line to remove cuttings, sediment, or water from a borehole during drilling or development.

A clay rich in montmorillonite that swells when wet; used to make drilling mud, to seal boreholes, and as a grout component for annular seals.

Pipe installed in a completed borehole to hold the walls open, prevent collapse, and keep unwanted material out of the well; may be steel, PVC, or other approved material.

A mixture of cement and water, often with bentonite or additives, pumped into the annular space to form a hard, low-permeability seal around well casing.

A water-bearing layer bounded above and below by impermeable material, so its water is under pressure greater than atmospheric at the top of the layer.

Rock fragments and soil particles loosened by the drill bit and carried to the surface by drilling fluid or air; their appearance helps identify the formations being drilled.

The drop in water level in a well or aquifer caused by pumping, measured as the difference between the static water level and the pumping level.

A fluid mixture of water and clay or polymers circulated through the borehole to cool the bit, lift cuttings, and stabilize the borehole wall.

A pumpable material such as neat cement, sand-cement, or bentonite slurry used to fill the annular space and seal a well against surface water and cross-contamination.

The imaginary level to which water in a confined aquifer would rise under its own pressure if a measuring point were open to the atmosphere.

A method in which a rotating bit cuts the formation while drilling fluid or air circulates to remove cuttings and stabilize the hole.

A rotary method that uses compressed air, often with foam, instead of liquid mud to cool the bit and carry cuttings out of the borehole.

A percussion method in which a heavy bit is repeatedly lifted and dropped on a cable to break rock, and a bailer removes the loosened material.

Slotted or perforated pipe installed at the producing zone of a well to admit water while holding back sand and gravel from the formation.

A graded body of clean gravel or coarse sand placed around a well screen to filter formation material and improve flow into the well.

The process of removing drilling mud, fines, and loose sediment from the borehole and surrounding formation so the well yields clear water at its best capacity.

The level of water in a well when it is not being pumped and has had time to recover to its natural, undisturbed position.

The water level in a well while it is being pumped at a steady rate, after drawdown has stabilized.

The yield of a well divided by its drawdown, usually expressed in gallons per minute per foot of drawdown; a measure of well efficiency.

A controlled pumping or bailing test that measures how much water a well produces and how the water level responds, used to select and set the pump.

A water-bearing layer whose upper boundary is the water table, open to the atmosphere through overlying permeable material.

The above-ground top of a well, including the casing end, cap or seal, and any vent, which must be finished to keep surface water and debris out.

A pipe lowered into the annular space to deliver grout from the bottom upward, preventing voids and dilution during well sealing.

The depth at which a submersible pump is installed in a well, chosen so the intake stays submerged while the motor has enough flow past it to stay cool.

The vertical pipe that carries water from a submersible pump up to the surface; it supports the pump assembly and must resist pressure and weight.

A multistage centrifugal pump and its motor, sealed as a unit and installed below the water level in a well to push water to the surface.

A shallow- or deep-well pump that uses a venturi nozzle and pressure to move water; the ejector may be at the surface or down in the well.

A one-way valve at the bottom of a suction line that lets water in but prevents it from draining back, keeping the pump primed.

Filling a pump and suction line with water before starting, so the pump can create suction instead of running dry.

A tank with a trapped air charge that stores water under pressure, letting the pump run less often and keeping system pressure steady.

A device that starts the pump at a low pressure set point and stops it at a high set point, controlling the tank pressure range.

A rubber device fitted on the drop pipe above a submersible pump that centers the pipe and absorbs twisting force when the pump starts.

A one-way valve in the discharge line that stops water from flowing backward through the pump when it shuts off, protecting the pump from spin-back.

The ratio of the hydraulic power delivered by a pump to the power it consumes; lower efficiency raises operating cost and can indicate wear.

A graph supplied by the manufacturer showing how a pump's flow rate, head, and power draw change across its operating range.

The total pressure a pump must overcome, combining lift, discharge pressure, and friction losses in the piping system.

A tight-fitting cover on the top of the well casing that keeps out surface water, insects, and debris while allowing a vent for air movement.