The occupied West Bank faces grave water shortages largely as a result of "discriminatory" Israeli policies, an Israeli human rights group said on Tuesday.

"The shortage will have serious repercussions on the economy and the health of tens of thousands of Palestinians," the B'Tselem group said in a statement.

"The chronic water shortage results in large part from Israel's discriminatory policy in distributing the joint water resources in the West Bank, and the limits it places on the Palestinian Authority's ability to drill new wells," it said.

The accumulated effects of a series of dry years will make the shortages even worse in coming months.

Per capita water consumption in the West Bank stands at 66 litres (just over 17 gallons) a day, about two-thirds less than the minimum recommended by the World Health Organisation.

Per capita water consumption by Israelis is 3.5 times that of Palestinians, B'Tselem said.