In Zambia, boreholes are regularly drilled in both rural and urban areas to provide water for industrial as well as domestic use. Borehole companies often offer complete packages that include hydro-geological surveys, water well drilling, storage tanks, pump installations and testing. This Infobwana section includes enterprises that provide borehole and drilling services as well as pumps powered by electricity, solar or wind.
Boreholes are one of the best means of accessing clean water. In Zambia, they are drilled using a motorised drilling rig. This undertaking requires specialised knowledge and technical expertise, which is readily available.
Boreholes vary in design and depth depending on the level of the water table, the quantity of water stored in the ground and the requirements of the customer. Typically they are between 60 - 120 metres deep. In basic terms, there are usually two pipes involved in the final borehole installation – an outer metal pipe (casing), and a plastic inner pipe that slides down inside it, with the lower segments of the pipe slotted to allow water access. Normally the inner pipe is at least 4" in diameter to accommodate a 3” or 4” borehole pump. The piping must be surrounded by gravel to prevent dirt clogging up the plastic pipe, and it must be sealed near the surface using a special grout. This grout usually goes down as far as the impermeable ground layer and is designed to avert contamination from surface water entering the borehole. The outer metal casing pipe is usually required to be at least 6" in diameter.
Are you going to find water?
Companies can undertake preliminary assessments to avoid a dry borehole. This is to give you an increased chance of finding water suitable for your requirements. However, drilling any borehole involves risk - the borehole may have to be drilled deeper than planned; the water may not be of the required quality, or the water output may not be sufficient.
To reduce the risk, it is advisable that a hydro-geological assessment is conducted prior to drilling, and the drilling contractor's terms and conditions are checked carefully.
Pumps and equipment
Once the borehole is drilled and lined, the pump can be installed. Pumps and related equipment and accessories can be purchased from reliable suppliers. Some of these companies are also able to provide full installation services as well as maintenance and repair.
Before installation, the company will identify the client's requirements and offer one or more design options. Once agreed, engineers and project managers ensure the equipment is correctly sourced and installed, and fully commissioned. Full service and maintenance packages are available upon request.
Turnkey project steps (based on pump solutions):