Boreholes and alternative supplies

What is a borehole?

A borehole is a narrow shaft drilled into the ground, either vertically or horizontally, designed to access groundwater. This groundwater, naturally filtered through layers of rock and soil, is typically of high quality and can be used for various applications, including industrial processes, irrigation, and drinking water after suitable treatment. A well-constructed borehole, equipped with a vertical pipe (casing) and well screen, ensures that the borehole remains stable and guards against surface pollutants, whilst also protecting the pump from drawing in contaminated materials. Groundwater is one of the most valuable natural resources, providing a dependable and secure water supply when properly accessed and managed.

Implementation and costs

Constructing a water borehole involves the use of a drilling rig, either rotary or percussion, which can penetrate much deeper into the water table than traditional hand excavation methods. Modern drilling techniques result in boreholes that are typically narrower and deeper than traditional wells, allowing for a consistent and reliable water source. During the drilling process, steel or plastic casing is installed to prevent the borehole walls from collapsing and to block contaminants.

The drilling process starts by accessing the aquifer, with the depth varying greatly based on the area’s geological conditions. After the borehole is drilled, it is cased, sealed, and lined. A well screen is then fitted, and a submersible pump is installed. This pump draws water up through the rising main and channels it through a discharge pipe to a pressure tank, where the well water is stored before being delivered to its destination. In the UK, you can extract up to 20,000 litres of water per day from a borehole without needing a licence. For boreholes deeper than 15 metres, a borehole log must be submitted to the British Geological Survey. The borehole can be finished above or below ground based on the client’s preference. Thanks to modern drilling methods, water boreholes have become more reliable than traditional wells as a source of clean water.

Whilst the initial installation costs may seem high, the water can be used for various purposes, leading to long-term cost savings. High-water users typically see a return on investment within a few years. However, drilling a water well does not have a fixed cost due to numerous variables. These factors include the area’s geology, the depth and width of the borehole, its intended purpose, the type of pumps and equipment needed, as well as the machinery, labour, materials, and performance and quality testing involved.

Proper maintenance is essential for ensuring a borehole’s long-term efficiency and reliability. Water yield can be affected by mechanical and chemical blockages that restrict flow, as well as bacteriological plugging caused by bacteria and microorganisms. Pump failures or malfunctions can also interfere with water extraction. To prevent these issues, it is important to schedule annual maintenance checks with a professional, keep the surrounding area clean and free of chemicals, and test water quality regularly to identify and address potential problems promptly. Proper maintenance ensures that the borehole continues to provide a reliable water source and extends its operational lifespan.