Palestine is a geographic region in Western Asia between the Mediterranean Sea and the Jordan River. It has a total land area of 27,009 km² and a population of 11.8 million people according to the Palestinian estimates in 2013.
The climate in the Palestinian territory is Mediterranean in its basic pattern, and varies from semi-arid in the west to extremely arid in the east and southeast; it is characterized by long, hot, dry summers and short, cool, rainy winters, as modified locally by altitude and latitude. The climate is determined by the location between the subtropical aridity characteristic of Egypt and the subtropical humidity of the eastern Mediterranean area.
About 70 percent of the average rainfall in the country falls between November and March; June through August are often rainless. Rainfall is unevenly distributed, decreasing sharply as one move southward. In the extreme south, rainfall averages less than 100 mm annually; in the north, average annual rainfall is about 1,100 mm. Rainfall varies from season to season and from year to year. Precipitation is often concentrated in violent storms, causing erosion and flooding .
Groundwater is the main source of water for the Palestinians in the West Bank and Gaza Strip and provides more than 90% of all water supplies. Following the 1967 occupation, Israel controls all shared water resources including surface and groundwater, and utilizes more than 85% of these resources, leaving less than 15% for Palestinian use. The surface water in Occupied Palestine is represented by several seasonal wadis, as well as the Jordan River, which is currently controlled and used exclusively by the Israelis .
Occupied Palestine is among the countries with the scarcest renewable water resources per capita; average domestic water consumption is only 72 l/c/d in the West Bank; it is higher at 90 l/c/d in Gaza (but the water quality there is far below all standards). This is significantly below the per capita domestic water delivery in other countries in the Middle East, constraining economic development, increasing infrastructure and running costs and possibly leading to health problems. More than half of the available groundwater is used for domestic water supply, severely limiting the available volume for industry and especially irrigated agriculture .
The water situation in Gaza is much worse than on the West Bank. In general, for 2012 the total local water resource (including wells and springs) available for all purposes for Palestinians was some 289 MCM; about 104 MCM in the West Bank and about 185 MCM in Gaza Strip .
Desalination of brackish water to achieve acceptable levels of drinking water quality is an important option that is implemented in the West Bank on a limited scale. In Gaza it is presently implemented at local scale only, although it is a key requirement in water resources management and very urgent. The most important accomplishment is the start of the expansion of the existing Deir El Balah seawater treatment plant from a capacity of 0.22 MCM/y to 0.95 MCM/y (2600 m3/day) .