I. From point of view of water-bearing layer:
From point of view of selecting the proper type of well it is very important what purpose is the abstracted water for. The shallow water well implemented on groundwater aquifer of poor quality is even suitable for satisfying irrigation respectively industrial water demands. On the other hand, in case of satisfying drinking-water demands, it is recommended to implement the planned wells on deeper, more protected layer or karstic water aquifer of better quality.
II. From point of view of implementing technology:
Dug wells were used for extracting water from shallow aquifer for domestic water supply. Since their implementation is expensive, their water quality is not suitable for human consumption and their water output is uncertain, this type of well is not made anymore. And what is more, the existing wells are used less and less in smaller settlements.
In practice, the water wells are now almost exclusively drilled for water extraction. The advantage of the professionally drilled wells is that they can be drilled almost everywhere, with different diameters and depths, depending on the geological and hydrogeological conditions, their water output is constant even for decades and water quality is appropriate excepting that implemented on groundwater aquifer. A further advantage is that it can be separated from the environment, can be protected from pollution with the required well-head.
III. From point of view of drilling method
When applying dry drilling method we use cascade drilling method without flushing where the boring silt will be dredged with elutriating apparatus, auger drill, mud auger or core drill.
This method is generally used for wells and exploring bore-holes implemented on gravel terraces (completed with soil mechanics tests).
Flush boring method is a continuous drilling method where the boring slit will be dredged with drilling mud circulated in the bore hole. The further important function of flushing is the counterbalancing of the pressure respectively stabilization of bore hole wall.
This method is used almost exclusively for exploring anemoclastic rock, clay media and sabulous layers.
Air-drilling is a drilling method, similar to flush drilling process, is a continuous drilling method where the boring slit will be dredged by large quantity of compressed air.
It is used mainly for traversing compact, dry, exfoliated rock of high solidity. In case of flush flow-in during drilling, the air-drilling will be completed by surface-active, foaming agents.