Shallow Wells:

These wells are in the upper layers of the earth's strata, usually less than 30 metres deep. The water which enters a shallow well is derived from shallow percolation and, therefore, not perfectly purified by natural process. The amount, distance and nature of immediate pollution and the character of underlying strata determine to a large extent, the purity of such water. Location of shallow wells with respect to known pollution source is one of the important criteria in the use of water, especially when large quantities are to be withdrawn.

Unsafe bacteriological condition results if there is carelessness in construction of shallow wells. Dug wells are to be covered with concrete water-tight wall a few meters below the vertical zone of pollution, which usually extends around four to five meters below normal surface level. The lining wall should extend about a metre above the surface grade and cover should be attached with a water tight joint and a man-hole. Driven well is the safest form of shallow wells. Still they should be driven ten metres and more to provide the required degree of protection.