Drilling has over the years developed to a highly specialized and technical activity. Drilling with rigs as in the olden days rarely takes place and most of the water wells drilled are drilled with the air percussion technique. This technique is fast and efficient.

However, when drilling a water well for groundwater abstraction purposes, drilling becomes much more than just making a hole in the ground.

For many people drilling is only the activity above the ground that they can see and observe. A water well is however a specially engineered hole in the ground, making provision for water to flow into this hole and allowing for a pump to be installed inside the hole to allow abstraction of water. Part of this engineered design is to prevent the surrounding geological formations to collapse and closing the water well. This could mean cost and energy to re-drill or clean the hole to be able to use it again. The task of the Driller is to drill and construct a water, not to get water. This task should be left to the scientist dealing with the nature and study of the geological formations. None can however operate in isolation and it important to see the actions of the scientist and driller as a team effort.

There are very few people that take time to consider how the drillers manage to keep a vertical borehole, which went through sand and hard rock, open until the casing is installed. How does one manage to remove the drilled pieces of rock from deep below the surface? Skill is needed to guide and control a water well drill as it penetrates sand, gravel, clay and solid rock formations underground. The drill rods are quite heavy and can weigh several tons; if the drill pushes too hard or turns too fast, the drill bit will wear out too fast; if it does not push hard enough, it won’t penetrate. Quite often several rock layers are encountered in a single borehole, each requiring different drilling pressures and speeds. When water is encountered the drilling becomes even more complicated and the driller needs to understand exactly what forces need to deal with to further penetrate.

Two methods are typically used in India for the drilling of water boreholes, these being the rotary and air percussion methods. A third method the cable tool method used to be quite popular, but due to the time it takes to drill a hole with this technique it is not quite as popular any more. There are other methods, and combinations of methods, but these are the most common. Most home wells are drilled to 4 1/2" or 6 1/2" inches in diameter. Municipal or irrigation wells are likely to be drilled at larger diameters, sometimes as much as 12 inches or more.