The wells can be broadly divided into two categories:- open or dug wells and tubewells.

Tubewells are those types of wells used to achieve high discharge rates. A tubewell is a long pipe or tube bored or drilled deep into the ground to intercept one or more water-bearing strata.

The tubewells can be broadly classified into:- shallow tube well, deep tube well, cavity-type tube well, screen-type tube well and slotted-type tube well.

A shallow well draws water from the topmost water-bearing stratum and is susceptible to contamination from percolating rainwater. Furthermore, the yielding capacity of shallow wells is very low. In contrast, a deep well is built on an impervious 'mota' layer and draws its supply from the pervious formation beneath the 'mota' layer via a bore hole drilled into the 'mota' layer. As a result, a deep well can provide a higher discharge and greater supplies than a shallow well without the water being contaminated.

These types of wells can reach depths of up to 300 metres and tap into more than one aquifer. In our country, they are typically built by state governments and are known as State Tubewells. Such wells can produce up to 200 to 220 litres per second.