In many nations where rivers and drainage systems are insufficient, groundwater has replaced them as the primary source of water used in agriculture. As a result, in recent years, low groundwater quality for irrigation purposes has raised concerns. Groundwater pollution is a result of inadequate or excessive use of chemical fertilizers .The quality of groundwater is influenced by the type of recharging water, precipitation, subsurface and surface water, hydro-geochemical processes in aquifers, changes in land use and land cover, and mining activities. Periodic changes in groundwater quality are usually caused by temporal changes in the makeup and source of the water recharged, as well as by human activity. Groundwater quality deteriorates in two ways: first, as a result of geochemical reactions in the soils and aquifers, and second, when it is provided for irrigation through inefficient canals or drainages. Therefore, it is essential to regularly evaluate the quality of drinking and irrigation water. A sufficient amount of usable water must be available for irrigation. Irrigation demands sufficient water supply of usable quality. It may be helpful to use an index based on the composition and concentration of dissolved components in water to assess whether it is suitable for agricultural use. The type of mineral components present in the water and how they affect the soil and plants determine whether or not groundwater is suitable for irrigation. This paper reviewed groundwater hydro chemistry of the Indo Gangetic Plain region in relation with irrigation and overexploitation of groundwater. Also considering the changes in the physico-chemistry of the aquifers of the region, with respect to monsoon. It was observed that in most of the IGP regions water quality becomes unfit for irrigation purpose during post-monsoon due to leaching of pollutants. High concentration of various salts and heavy metals in the groundwater was also found due to the high siltation, erosion and leaching activities.
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