Groundwater is an important source of water in Thailand. Public water supply for one fifth of the nation’s 220 towns and cities and for half of the 700 sanitary districts is derived from groundwater. It is estimated that 75 percent of domestic water is obtained from groundwater sources. The groundwater system in Thailand is mainly recharged by rainfall of about 40 000 million m3 and by seepage from the rivers.
Hydrological balance studies estimate that about 12.5 to 18 percent of the rainfall would infiltrate the soil and about 9 percent reach the aquifer.