Ground water is mainly recharged by rainfall and seepage streams. Aquifers yield a large amount of water throughout Thailand, with the exception of the Eastern region. The largest source of groundwater is found in the Lower Central Plain, particularly in Bangkok Metropolitan Region (BMR) and surrounding provinces, and is being used to meet the growing water demand.* Unlike the other regions, some ground water extraction data is available for the central region.
Agricultural run-off, coastal aquaculture, industrial effluents and domestic sewage are responsible for the pollution of groundwater in Thailand. Also, the lack of an appropriate pricing policy is leading to over-exploitation of groundwater beyond sustainable yield levels. There is limited information on groundwater extraction rates, or the extent of contamination at the national level.