Abstraction Licence: Required by the Environment Agency for borehole owners who wish to use more than 20 cubic metres (20 000 litres) of water per day.

Aquifer: The material that holds the groundwater, this can be chalk, gravel, porous or fissured stone.

Artesian well: A well or water borehole where the underground pressure forces the water to the surface, sometimes even causing a spout or fountain.

Auger: Long, corkscrew shaped drill bit used usually for drilling shallow boreholes in soft ground.

Bentonite: A clay material which expands on contact with water. Used to seal the top part of water boreholes to prevent ingress of contaminants.

BGS: British Geological Survey.

Bit: Sharp carbide or diamond tipped tool for drilling through hard materials.

Booster pump: Electric submersible pump located in buffer tank. Controlled by pressure or flow sensor. Provides pressure in domestic water or irrigation system.

Buffer Tank: Water tank in water borehole installation to provide reserve in case of borehole stoppage. Contains booster pump to pressurise house or irrigation system.

Casing: see also liner. The pipe that stops the wall of the borehole collapsing.

Closed loop system: GSHP system in which the heat conducting medium is in a sealed (closed) loop and never comes into direct contact with the ground or environment.

COP: The steady-state performance of an electric compression heat pump at a given set of temperature conditions is referred to as the coefficient of performance (COP). It is defined as the ratio of heat delivered by the heat pump and the electricity supplied to the compressor.

Drawdown: The reduction in level of water in the water borehole resulting from prolonged pumping.

Drill rods: The hollow rods forming the shaft on which the drill bit is mounted.

Electrofusion Welding: Modern technology using electrothermal heating to weld plastic pipe fittings to produce a permanent heavy duty joint.

Flush: Drillers term for the recirculating water that brings drilling debris up the borehole to the surface.

Geothermal Loop: High density polyethylene pipe used to conduct heating medium in and out of borehole. Must be pressure rated 16 Bar and quality PE100 (Not PE80!).

Gravel Pack: Fine gravel used to surround water borehole screen to act as filter, preventing ingress of particles, silt, sand to borehole.

GSHP: Ground Source Heat Pump, heat pump using geothermal heat as opposed to e.g. Air Heat.

Groundwater: Our most important freshwater reserve. Part of the water cycle. Vast reserve of water held in permeable rock layers.

Grout: Special semi liquid material which fills the space between the geothermal loop and the borehole walls. Conducts ground heat to the loop collector.

Liner: see also casing; The pipe that stops the wall of the borehole collapsing. Usually made of high density plastic.

Manifold: Apparatus for combining and balancing flows from several boreholes to give single in/out flow to heat pump.

Mud Pump: the heavy duty pump that recirculates the water through the drill rods to lubricate the drilling action in a rotary drill.

Mud Puppy: American invented unit to separate drilling mud and debris from recirculating water allowing much cleaner drilling operation.

Open loop system: GSHP system in which the heat conducting medium i.e. water is pumped out of one borehole, fed through the heat exchanger in the GSHP and returned to the ground, usually via a second, soakaway borehole.

Percussion Drill Rig: Drilling apparatus that drops a sharp drill bit from height, thus penetrating the ground to form borehole.

Rotary Drill Rig: Drilling machine which drives a rotating bit into the earth. Rather like a Black & Decker drill!

Riser Main: Vertical pipe which brings the water from the borehole pump up to the surface.

Temporary Casing: A metal tube inserted into the borehole to prevent the collapse of the borehole during the drilling operation. After drilling is completed it is withdrawn.

Thermal Conductivity: The thermal conductivity of the ground indicates how easily heat moves to and from the fluid in the ground loop.

Tremie: A pipe used to feed liquid grout down a borehole, often to beneath water level.

UKAS: United Kingdom Accreditation Service. Government controlled body certifying capability of e.g. analytical laboratory to work to prescribed standards.

Water Borehole Survey: Geological Survey detailing geological strata beneath the borehole site and estimating the likely depth of the water table.

Water Table: The level at which the groundwater resides beneath the surface.

Wellhead: The top of the borehole, on or just under the surface. Usually comprises manifolds, valves, joints, to take the borehole water horizontally to its next destination. Usually housed in underground chamber.

Our apologies for the repeated use of the titles water boreholes and geothermal boreholes on these pages; such are the dictates of search engine requirements.

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