Open wells are the wells which have comparatively large diameters but low yields (or discharges) and are not very deep. The diameters of the open wells usually vary from 1 m to 10 m. The yield of such wells in most of the cases is about 20 m³/hour or less. However, a properly constructed open well penetrating a permeable aquifer can yield 100 to 300 m³/hour. 

The depths of open wells may generally range from 2 m to 20 m. Since these wells are usually constructed by digging, these are also known as dug wells. The walls of an open well may be built of brick or stone masonry or precast concrete rings. The thickness generally varies from 0.5 m to 0.75 m depending on the depth of the well.

Open wells may be further classified as:

(a) Shallow open wells

(b) Deep Open wells

Shallow open wells are those which rest in the top water bearing strata and draw their supplies from the surrounding material. On the other hand deep open wells are those which rest on impervious strata and draw their supplies from the pervious formation lying below the impervious strata through bore holes made in the impervious strata. 

The impervious strata is generally known as mota layer and it is a layer of clay, cemented sand, kankar or other hard materials. The term mota layer is however not applied to layers of hard materials laying above the water table. 

The main advantage of such a mota layer is that it gives structural support to the open well resting on its surface. Further since the pervious formation below the mota layer generally contain large quantity of water, the yield of deep wells is more than that of shallow wells.

It may, however, be mentioned that the nomenclature of shallow and deep open wells is purely technical and it has nothing to do with the actual depth of the well because sometimes a shallow well may have more depth than a deep well.