Borehole Drilling Terms You Need to Know Vol. 1

Thinking about getting a water borehole, but don’t really know how it works or where to start? With the dams drying up, the municipal water costs going up, and the people getting fed up; it is more important than ever to understand and consider alternative water sources. As you begin your research in borehole drilling, we’ve compiled a list of terms you’ll come across when dealing with borehole drilling companies. Aquifer – A water bearing layer of sediment or rock with interconnected pore spaces or fractures that can store and deliver water to a borehole or spring. Borehole – The cylindrical hole drilled into the ground and aquifer. Casing – Steel or PVC pipe placed in the borehole to keep the borehole open and to allow room to store water and install a pump. Average casing depths in Gauteng are 12-24m (some holes may require casing from surface to the end of the borehole). Cement or Bentonite – Placed between the wall of the borehole and the casing and surface casing to prevent surface contamination from reaching the aquifer. Cistern – A vented water holding tank, usually above ground, used for storage of water before being delivered to the pressure tank and home. Cisterns come in varying sizes – typical sizes are 2500L, 5000L & 10 000L. Control Box – Electrical switch box that turns the well pump on and off. Drop Pipe – Pipe placed in the casing to connect the pump to the surface. Electrical Cable – Wiring from the pump control box to the pump that supplies power for the pump and command signals. End Cap – Cap placed on the bottom of the casing – if the casing extends to the bottom of the borehole and gravel packed to prevent sediment from flowing into the casing on a screened well. Gravel Pack – Gravel or sand placed between the borehole wall and the well screen to keep the borehole open and filter water before it enters the well. Groundwater – Water stored beneath the surface of the earth that is transmitted through small, interconnected pores and fractures in hard rock. Pressure Tank – A water holding tank equipped with an air bladder that regulates water pressure into the home and demand to the pump. Pumping Water Level – The depth below the ground surface of the water level in the well when the pump is operating. This is always deeper than the static water level. Sanitary Well Cap / Base Plate – A vented and vermin proof cap on the top of the well casing that prevents surface contaminants from entering the inside of the well. Spring – Water flowing directly from an aquifer on to the surface. For drinking water the spring is usually surrounded by a spring house which protects the spring from outside contamination. Submersible Pump – A common type of water well pump includes the pump and pump motor placed at the bottom of the drop pipe below the pumping water level. Static Water Level – The depth below ground surface of water when the pump is not operating. This level will vary seasonally and over longer time periods due to recharge, drought or groundwater mining. Treatment Equipment – Can include a variety of equipment designed to remove various water contaminants and purify groundwater before use. Water Table – The upper surface of the zone where pore spaces are saturated as indicated by the static water level in an un-pumped well. Well, Screen – Steel or PVC perforated pipe that water from the aquifer flows through to enter the well and pump. In wells completed in bedrock, there may not be a well screen or gravel pack. For more articles like this check out our blog