Groundwater pollution due to anthropogenic activities may impact overall groundwater quality. Organic and inorganic pollutants have been routinely detected at unsafe levels in groundwater rendering this important drinking water resource practically unusable. Vulnerability of groundwater pollution and subsequent impact has been documented in various studies across the globe. Field studies as well as mathematical models have demonstrated increasing levels of pollutants in both shallow and deep aquifer systems. New emerging pollutants such as organic micro-pollutants have also been detected in some industrialized as well as in developing countries. Increased vulnerability coupled with ever growing demand for groundwater may pose a greater threat of pollution due to induced recharge and lack of environmental safeguards to protect groundwater sources. In this review paper, comprehensive assessment of groundwater quality impact due to human activities such as improper management of organic and inorganic waste, and natural sources is documented. A detailed review of published reports and peer reviewed journal papers across the world clearly demonstrate that groundwater quality is declining over time. A proactive approach is needed to prevent human health and ecological consequences due to ingestion of contaminated groundwater.