typically, a borehole is drilled by machine and is relatively small in diameter and a well is usually sunk by hand and is relatively large in diameter.
Of course, there are machines to sink large diameter wells and there are tools and equipment to drill boreholes by hand, but for all intents and purposes, the above description is applicable in Kenya.
Wells originally were sunk by hand using bricks or rocks as the well liner. The bricks were sunk by their own weight, in other words, the bricks were added from the surface and the poor well sinker would excavate undermining the well walls, hence the term well sinker. This was an extremely difficult and dangerous task and as the sinking was in progress candles were used to test the air for possible leakage of gas/foul air and as a means of illumination. Believe it or not we still used candles up to approximately 20 years ago. Nowadays we are fortunate to have flashy electronic gas detectors.
Today if we are sinking a new well, we would not use bricks but instead concrete rings, although still an arduous task it is considerably faster and safer.
Boreholes many years ago would have been bored by the percussion method which would entail driving down a steel liner. Occasionally this method may still be used today, but more often than not the bores are lined with PVC. Sections of the borehole are unlined if the formation is self-supporting, for example in sandstone or chalk.
The main advantage of a borehole is that it is possible to penetrate the aquifer to a greater depth ensuring a reliable supply in times of drought or high usage.
Borehole drilling companies hope that their brief description may have helped any of you out there confused by the terminology.
Often when clients call stating that they have a deep well, we always ask is it large in diameter i.e. approximately 4ft brick-lined or concrete rings or narrow in diameter 4” to 6” steel lined or PVC.