Water may be obtained from surface water resources like streams, rivers, tanks, ponds and lakes or it may be obtained from subsurface resources through open dug-wells and tubewells. In the past when human populations were smaller both on were smaller both on a regional and global scale, surface water resources were sufficient for human sustenance but today when populations have increased tremendously these resources are insufficient and so alternative resources from subterranean water have to be exploited to meet with the needs. The distribution of both surface and subsurface water is uneven and so the population densities vary according to the water availability in a region.

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Keywords: Water Resources, Potability, Human Sustenance, Subterranean Water, Subsurface Water.