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Jordan is classified as an and to semi-arid country with a population according to 1999 estimates of 4.8 millions inhabitants and a growth rate of 3.4%. Efficient use of Jordan’s scarce water is becoming increasingly important as the urban population grows. This study was carried out within the framework of the joint European Research project ’Groundwater recharge in the eastern Mediterranean’ and describes a combined methodology for groundwater recharge estimation in Jordan, the chloride method, as well as isotopic and hydrochemical approaches. Recharge estimations using the chloride method range from 14 mm year(-1) (mean annual precipitation of 500 mm) for a shallow and stony soil to values of 3.7 mm year(-1) for a thick desert soil (mean annual precipitation of 100 mm) and values of well below 1 mm year(-1) for thick alluvial deposits (mean annual rainfall of 250 mm). Isotopically, most of the groundwater in the Hammad basin, east Jordan, falls below the global meteoric water line and far away from the Mediterranean meteoric water line, suggesting that the waters are ancient and were recharged in a climate different than Mediterranean. Tritium levels in the groundwater of the Hammad basin are less than the detection limit (<1.3 TU). However, three samples in east Hammad, where the aquifer is unconfined, present tritium values between 1 and 4 TU. Copyright (c) 2007 John Wiley & Sons, Ltd.