Dear Vidhya, it's clear ...

Dear Vidhya,

it's clear that water quality must be monitored at both surface water bodies and groundwater wells. How to prevent groundwater contamination from surface contamination is the big question. The answer is, indeed, site dependent. It all depends on local geology. Normally, wells in Quaternary aquifers tap three main geological units: (1) a shallow aquifer, (2) a deep aquifer and (3) an aquitard in between them. Wells are in many cases drilled to tap only the shallow aquifer because it's cheaper (100-200 meters). Indeed, it's the shallow aquifer the one that interacts more with surface water and therefore, with potential pollutants. Instead, if wells are screened only at the deepest section, the impact of surface contamination is alleviated.

Having said so, ideally the best solution is to eradicate pollution at the source. This can be achieved by implementing strong penalties to contaminating industry, etc.